2.A.29 The Mitochondrial Carrier (MC) Family

Permeases of the MC family (the human SLC25 family) possess six transmembrane α-helical spanners. The proteins are of fairly uniform size of about 300 residues. They arose by tandem intragenic triplication in which a genetic element encoding two spanners gave rise to one encoding six spanners (Palmieri 2012; Wang et al. 2016). This event may have occurred less than 2 billion years ago when mitochondria first developed their specialized endosymbiotic functions within eukaryotic cells. Members of the family are found exclusively in eukaryotic organelles although they are nuclearly encoded. Most are found in mitochondria, but some are found in peroxisomes of animals, in hydrogenosomes of anaerobic fungi, and in amyloplasts of plants. Members of the MC family are functional and structural monomers although early reports indicated that they are dimers (Bamber et al., 2006, 2007). Many of them preferentially catalyze the exchange of one solute for another (antiport). Fifteen paralogues of the MC family are encoded within the genome of Saccharomyces cerevisiae. Fifty have been identified in humans. 58 in A. thaliana and 35 in S. cerevisiae. The functions of many of the human homologues are unknown, but most of the yeast homologues have been functionally identified. Functional aspects have been reviewed by Palmieri (2004), Palmieri et al. (2006) and Plamieri and Pierri (2010).  Diseases caused by defects of mitochondrial carriers are reviewed by Palmieri et al. (2008) and by Gutiérrez-Aguilar and Baines 2013. Residues involved in substrate binding in the middle of the transporter and gating have been identified and analyzed (Monné et al. 2013).  The physiology and pathology of MCs has been reviewed (Palmieri and Monné 2016).

Members of the mitochondrial carrier family are involved in transporting keto acids, amino acids, nucleotides, inorganic ions and co-factors across the mitochondrial inner membrane. The transporters are thought to share the same structural fold, which consists of six trans-membrane alpha-helices and three matrix helices, arranged with threefold pseudo-symmetry. There are 53 MC homologues in humans. During the transport cycle two salt bridge networks on either side of the central cavity might regulate access to a single substrate binding site in an alternating fashion. In the case of proton-substrate symporters, the substrate binding sites contain negatively charged residues that are proposed to be involved in proton transport (Kunji and Robinson, 2010). Wang et al. 2016 haved reviewed the structures and transport mechanisms of these porters.

The high resolution 3-D structure of the human homologues one MC family member, the bovine ATP/ADP antiporter (TC #2.A.29.1.1), has been solved by x-ray crystallography to 2.2 Å resolution (Pebay-Peyroula et al., 2003; Klingenberg et al., 2008). The carrier was crystalized in complexation with the inhibitor, carboxyatractyloside. The six TMSs (with the N- and C-termini normally facing the cytoplasmic side of the membrane and the three hairpin loops of the repeat sequences facing the matrix) form a compact barrel domain which shows a deep cone-shaped depression at the surface facing the intermembrane space. At its base was found the signature sequence of these nucleotide carriers (R R R M M M). The cavity has a maximal diameter of 20 Å and a depth of 30 Å. The fold of the three repeat elements is very similar. Each odd-numbered helix exhibits a sharp kink, due to a conserved prolyl residue located in the conserved P X(D/E) X X (K/R) motif, characteristic of all mitochondrial carriers. The even-numbered helices pass straight through the membrane without a kink. The structure reveals large hydrophilic surfaces in the interior of the conical pit, due to the weak hydrophobicities of these proteins. A positive electrostatic surface potential on the matrix side and at the bottom of the pit provides the force for anionic substrate binding. Two lipid molecules, both cardiolipin molecules, are tightly bound to the carrier.

The mitochondrial uncoupling protein 2 structure has been determined by NMR molecular fragment searching (Berardi et al., 2011). UCP2 closely resembles the bovine ADP/ATP carrier, but the relative orientations of the helical segments are different, resulting in a wider opening on the matrix side of the inner membrane. Nitroxide-labelled GDP binds inside the channel and seems to be closer to transmembrane helices 1-4 (Berardi et al., 2011).

The transport substrates of MC family members may bind to the bottom of the cavity, and translocation results in a transient transition from a 'pit' to a 'channel' conformation (Kunji and Robinson, 2006; Robinson and Kunji, 2006). The inhibitor, carboxyatractyloside, probably binds where ADP binds, in the pit on the outer surface, thus blocking the transport cycle. Another inhibitor, bongkrekic acid, is believed to stabilize a second conformation, with the pit facing the matrix. In this conformation, the inhibitor may bind to the ATP-binding site. Functional and structural roles for residues in the TMSs have been proposed (Cappello et al., 2006, 2007). The mitochondrial carrier signature, Px[D/E]xx[K/R], of carriers is probably involved both in the biogenesis and in the transport activity of these proteins (Zara et al., 2007). A homologue has been identified in the mimivirus genome and shown to be a transporter for dATP and dTTP (Monné et al., 2007).

One of the MC family members, the uncoupling protein, UCP1 (TC# 2.A.29.3.1), functions to dissipate the proton motive force, thereby generating heat. This protein has been shown to be capable of transporting fatty acids, long chain alkylsulfonates and chloride. It is believed to allow transport of protons down their electrochemical gradient in a cyclic, fatty acid-dependent process by first exporting fatty acyl anions and then allow the free diffusion of the protonated fatty acid across the bilayer into the mitochondrion. UNC1 is therfore probably an anion translocator that may not require that transport occurs by an antiport mechanism. The fatty acid behaves as a cycling protonophore (Garlid et al., 2000). UNC1 uses coenzyme Q (ubiquinone) as a cofactor (Echtay et al., 2000). Like many other MC family members, uncoupling proteins are found in the mitochondria of plants as well as animals. Various compounds such as the reactive aldehyde (produced under oxidative stress conditions), 4-hydroxy-2-nonenal, as well as trans-retinal and other 2-alkenals activate uncoupling via UCP1-3 (TC #2.A.29.3.1) as well as the ATP/ADP antiporter (TC #2.A.29.1.1) (Echtay et al., 2003).

Mitochondrial uncoupling protein 1 (UCP1) is responsible for nonshivering thermogenesis in brown adipose tissue (BAT). Upon activation by long-chain fatty acids (LCFAs), UCP1 increases the conductance of the inner mitochondrial membrane (IMM) to make BAT mitochondria generate heat rather than ATP. UCP1 transports H+. UCP1 is an LCFA anion/H+ symporter (Fedorenko et al. 2012), but the LCFA anions cannot dissociate from UCP1 due to hydrophobic interactions established by their hydrophobic tails, and UCP1 effectively operates as an H+ carrier activated by LCFA. A similar LCFA-dependent mechanism of transmembrane H+ transport may be employed by other UCP members and be responsible for mitochondrial uncoupling and regulation of metabolic efficiency in various organisms and tissues.

Mitochondrial transporters have 3 homologous repeats and a structure with pseudosymmetry. Each repeat is folded into 2 transmembrane α-helices linked by a short α-helix on the matrix side and contains the signature motif PX[DE]XX[RK]. The proline residues kink the odd-numbered transmembrane α-helices, and the charged residues form a salt-bridge network connecting the C-terminal ends of the transmembrane α-helices, closing the transporter on the matrix side. During the transport cycle, the carriers form states in which the substrate-binding state of the carrier is open to the mitochrondrial intermembrane space and matrix, respectively. According to the single binding center-gating pore mechanism, interconversion of the 2 conformational states via a transition intermediate leads to substrate translocation. In the cytoplasmic state, a central substrate-binding site has been identified by applying chemical and distance constraints to comparative models. The substrates bind to 3 major sites on the even-numbered α-helices, which are related by symmetry and located approximately in the middle of the membrane. Yeast ADP/ATP carriers function as monomers (Bamberg et al., 2007).

Residues that are important for the transport mechanism are likely to be symmetrical, whereas residues involved in substrate binding will be asymmetrical reflecting the asymmetry of the substrates. By scoring the symmetry of residues in the sequence repeats, Robinson et al. (2008) identified the substrate-binding sites and salt bridge networks that are important for transport. The symmetry analyses provides an assessment of the role of residues and provides clues to the chemical identities of substrates of uncharacterized transporters.

The mitochondrion is one of the defining characteristics of eukaryotic cells, and to date, no eukaryotic lineage has been shown to have lost mitochondria entirely. In certain anaerobic or microaerophilic lineages, however, the mitochondrion has become severely reduced; it lacks a genome and no longer synthesizes ATP. One example of such a reduced organelle, called the mitosome, is found in microsporidian parasites. Only a few mitosomal proteins are encoded in the complete genome of the microsporidian, Encephalitozoon cuniculi, no proteins of the mitochondrial carrier family were identified. However, the microsporidian, Antonospora locustae, has a protein that is heterologously targeted to mitochondria in Saccharomyces cerevisiae (Williams et al., 2008). The protein is phylogenetically allied to the NAD+ transporter of S. cerevisiae, but it has high specificity for ATP and ADP when expressed in E. coli. An ADP/ATP carrier may provide ATP for essential ATP-dependent mitosomal processes such as Hsp70-dependent protein import and export of iron-sulfur clusters to the cytosol.

BID, a proapoptotic BCL-2 family member, plays an essential role in the tumor necrosis factor alpha (TNF-alpha)/Fas death receptor pathway in vivo. Activation of the TNF-R1 receptor results in the cleavage of BID into truncated BID (tBID), which translocates to the mitochondria and induces the activation of BAX or BAK. In TNF-alpha-activated FL5.12 cells, tBID becomes part of a 45-kDa cross-linkable mitochondrial complex. Grinberg et al. (2005) described the biochemical purification of this complex and the identification of mitochondrial carrier homolog 2 (Mtch2; TC# 2.A.29.25.2) as part of this complex. Mtch2 is similar to members of the mitochondrial carrier family. Mtch2 is an integral outer membrane protein exposed on the surface of mitochondria. Mtch2 resides in a protein complex of ca. 185 kDa, and the addition of TNF-alpha to these cells leads to the recruitment of tBID and BAX to this complex. Thus, Mtch2 is a mitochondrial target of tBID. The Mtch2-resident complex probably participates in the mitochondrial apoptotic program (Grinberg et al., 2005; Gross, 2005). 

The ADP/ATP carrier is electrogenic (electrophoretic), the GTP/GDP carrier is dependent on the pH gradient, the aspartate/glutamate carrier is dependent on both, and the oxoglutarate/malate carrier is independent of them (Monné and Palmieri 2014). The bovine ADP/ATP carrier consists of a six-transmembrane alpha-helix bundle with a pseudo-threefold symmetry and a closed matrix gate. By using this structure as a template in homology modeling, residues engaged in substrate binding and the formation of a cytoplasmic gate in MCs have been proposed. The functional importance of the residues of the binding site, the matrix, and the cytoplasmic gates is supported by transport activities of different MCs with single point mutations. Cumulative evidence has been used to postulate a general transport mechanism for MCs (Monné and Palmieri 2014).

The generalized transport reaction for carriers of the MC family is:

S1 (out) + S2 (in) ⇌ S1 (in) + S2 (out)

This family belongs to the Mitochondrial Carrier (MC) Superfamily.



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TC#NameOrganismal TypeExample

Mitochondrial ATP/ADP antiporter (SLC25A5 (300150)). Facilitates exchange of ADP and ATP between the cytosol and mitochondria (inhibited by carboxyatractyloside and bongkrekate) (Clémençon et al. 2013).  Modification of lysyl residues with fluorescamine induces Ca2+ permeability (Buelna-Chontal et al. 2014).


SLC25A5 of Homo sapiens


solute carrier family 25 (mitochondrial carrier; adenine nucleotide translocator), member 6

AnimalsSLC25A6 of Homo sapiens
2.A.29.1.2Mitochondrial ADP/ATP carrier 1 (AAC1); ADP/ATP translocase 1; adenine nucleotide translocator 1 (ANT1); adPEO, Sengers syndrome (SLC25A4)AnimalsSLC25A4 of Homo sapiens

Adenine nucleotide transporter, ANT, or ATP:ADP carrier AAC1 (one of three paralogues).  Transports heme and heme precursor protoporphyrin IX (PP IX) as well as ATP and ADP (Azuma et al. 2008).


AAC1 of Saccharomyces cerevisiae (P04710)

2.A.29.1.4The Hydrogenosome ADP/ATP carrier (Van der Giezen et al., 2002)FungiHydrogenosome ADP/ATP carrier of Neocallimastix frontalis (AAK 71468)
2.A.29.1.5ADP (Km = 40 µM)/ATP (Km = 100 µM) antiporter, ACC1 (three isoforms, AAC1, 2 and 3 were characterized where AAC3 has higher affinities (10-22 µM) (Haferkamp et al., 2002).PlantsACC1 of Arabidopsis thaliana
2.A.29.1.6The Endoplasmic Reticular Adenine Nucleotide Transporter, ER-ANT1 (probable ATP:ADP exchanger; Leroch et al., 2008)Plants ER-ANT1 of Arabidopsis thaliana (Q0WQJ0)

ADP:ATP carrier 2, Aac2 (Lethal with loss of Sal1, (2.A.29.23.2) but independent of its AAC activity (Kucejova et al., 2008)).  The x-ray structure suggests a novel domain-based alternating-access transport mechanism (Ruprecht et al. 2014).


Aac2 of Saccharomyces cerevisiae (P18239)


Mitochondrial ADP/ATP carrier.

AnimalsSLC25A31 of Homo sapiens

ADP/ATP carrier #3, AAC3 (90% identical to 2.A.29.1.7) (#2)). Prolines in TMSs 1,3, and 5 are important for function (Babot et al., 2012).  The x-ray structure suggests a novel domain-based alternating-access transport mechanism (Ruprecht et al. 2014).  Although the transporter catalyzes the translocation of substrate, the substrate also facilitates interconversion between alternating states (Brüschweiler et al. 2015).


ADP/ATP exchanger-3 (ACC3) of Saccharomyces cerevisiae (P18238)


TC#NameOrganismal TypeExample
2.A.29.10.1Flavin adenine dinucleotide (FAD) carrier (FADC; FLX1) (catalyzes FAD export from the mitochondrion) (Bafunno et al., 2004) Yeast FLX1 of Saccharomyces cerevisiae

Mitochondrial NAD /NADP carrier, NDT2; counter exchange substrates include ADP and AMP (Palmieri et al., 2009).


NDT2 of Arabidopsis thaliana (Q8RWA5)


Chloroplastic (plastidic) NAD /NADP carrier, NDT1; counter exchange substrates: ADP and AMP (Palmieri et al., 2009).


NDT1 of Arabidopsis thaliana (O22261)

2.A.29.10.2Mitochondrial folate transporter, hMFTAnimalsSLC25A32 of Homo sapiens

Chloroplast folate/folate derivative transporter, AtFOLT1 (Bedhomme et al., 2005; Haferkamp and Schmitz-Esser 2012)


AtFOLT1 of Arabidopsis thaliana (CAH65737)

2.A.29.10.4Mitochondrial pyrimidine nucleotide transporter, RIM2 (transports TTP (Km= 200 μM), UTP (Km= 400 μM) and CTP (Km= 440 μM). Catalyzes electroneutral TTP/TMP and TTP/TDP antiport. Deoxy pyrimidine nucleotides are also transported) (Marobbio et al., 2006). Pyrimidine trinucleotide transporter, RIM2 (transports TTP, CTP and UTP) (Todisco et al., 2006)YeastRIM2 of Saccharomyces cerevisiae
2.A.29.10.5The mitochondrial NAD+ uptake transporter, Ndt1 (also transports (d)AMP and (d)GMP but not α-NAD+, NADH, NADP+, or NADPH. Transport is saturable with an apparent Km of 0.38mM for NAD+). (70% identical to Ndt2 which also takes up NAD+). The main role of Ndt1p and Ndt2p is to import NAD+ into mitochondria by unidirectional transport or by exchange with intramitochondrially generated (d)AMP and (d)GMP (Todisco et al., 2006)YeastNdt1 of Saccharomyces cerevisiae (P40556)
2.A.29.10.6 solute carrier family 25 (pyrimidine nucleotide carrier ), member 36AnimalsSLC25A36 of Homo sapiens
2.A.29.10.7 solute carrier family 25 (pyrimidine nucleotide carrier), member 33AnimalsSLC25A33 of Homo sapiens

Mitochondrial nicotinamide adenine dinucleotide transporter 2, NDT2 (Mitochondrial NAD+ transporter 2) (Todisco et al. 2006).


YEA6 of Saccharomyces cerevisiae

2.A.29.10.9ADP/ATP-specific mitochondrial carrier (MC) in mitosomes (reduced mitochondria incapable of ATP synthesis) (Williams et al., 2008). MicrosporidianMC in Antonospora locustae (Q4VFZ9)

TC#NameOrganismal TypeExample
2.A.29.11.1The Plastid (Amyloplast) ADP-glucose transporter Brittle endosperm 1 (BT1) (Kirchberger et al., 2007).Plants BT1 of Zea mays
2.A.29.11.2The Adenine nucleotide uniporter, BT1 (Leroch et al., 2005).PlantsBT1 of Solanum tuberosum (Q9ZNY4)
2.A.29.11.3The plastid ADP-glucose transporter, Nst1 (~90% identical to and probably orthologous with 2.A.29.11.1.) (Haferkamp, 2007). PlantsNst1 of Hordeum vulgare (Q6E5A5)

Adenine nucleotide (ATP, ADP) carrier, ANT1; BRITTLE-1.  Present in both mitochondria and plastids (Haferkamp and Schmitz-Esser 2012).


ANT1 of Arabidopsis thaliana


TC#NameOrganismal TypeExample

Grave’s disease carrier (GDC) protein.  Transports coenzyme A and/or a coenzyme A precursor (Vozza et al. 2016). SLC25A16 is the human orthologue.


GDC of Bos taurus


Mitochondrial exchange transporter for Coenzyme A and adenosine 3', 5'-diphosphate, SLC25A42 (also transports dephospho-Coenzyme A, and ADP; Fiermonte et al. 2009).


SLC25A42 of Homo sapiens


solute carrier family 25; mitochondrial carrier; Graves disease autoantigen, member 16.  It is a Coenzyme A transporter (Gutiérrez-Aguilar and Baines 2013).


SLC25A16 of Homo sapiens


Mitochondrial Coenzyme A carrier protein, LEU5 or Leu-5 (Gutiérrez-Aguilar and Baines 2013).


LEU5 of Saccharomyces cerevisiae


Coenzyme A transporter of 331 aas (Zallot et al. 2013).


Coenzyme A transporter of Arabidopsis thaliana


Coenzyme A transporter of 325 aas (Zallot et al. 2013).


Coenzyme A transporter of Arabidopsis thaliana


Dephospho-coenzyme A (dPCoA) carrier, dPCoAC, of 365 aas and 6 TMSs. dPCoA is the best substrate, but ADP and dADP are also transported. Coenzyme A is not transported but is a strong competive inhibitor (Vozza et al. 2016).  Formerly called "alternative testis transcripts open reading frame A".

dPCoAC of Drosophila melanogaster (Fruit fly)


TC#NameOrganismal TypeExample

Succinate/fumarate antiporter, Sfc1, of 322 aas; essential for growth on ehtanol and acetate (Palmieri et al. 1997; Palmieri et al. 2006).


ACR1 of Saccharomyces cerevisiae


TC#NameOrganismal TypeExample
2.A.29.14.1Mitochondrial Ca2+-activated aspartate/glutamate antiporter carrier with Ca2+-binding EF-hand domain, Aralar AnimalsSLC25A12 of Homo sapiens

Calcium-binding mitochondrial carrier protein Aralar1 of 690 aas.

Aralar1 of Verticillium alfalfae (Verticillium wilt of alfalfa) (Verticillium albo-atrum)

2.A.29.14.2Mitochondrial Ca2+-activated aspartate/glutamate antiporter carrier with Ca2+-binding EF-hand domain, Citrin (defects in humans cause type II citrullinemia) AnimalsSLC25A13 of Homo sapiens

Mitochondrial glutamate carrier 1 (GC1); glutamate:H+ symporter 1 (SLC25A22). Plays a role in glucose-stimulated insulin secretion by β-cells (Casimir et al., 2009).  Also is responsible for migrating partial seizures in neonatal infancy (MPSI), a severe condition with few known etiologies (Poduri et al. 2013).


SLC25A22 of Homo sapiens


Yeast mitochondrial aspartate/glutamate antiporter, Agc1 (Cavero et al., 2003) (also catalyzes glutamate uniport and glutamate:proton symport (Palmieri et al. 2006). Comprised of 902 aas; has a 500 residue N-terminal hydrophilic domain as well as a C-terminal 100 residue hydrophilic domain. Both domains are uniquely found in members of the 2.A.29.14 subfamily.


Agc1 of Saccharomyces cerevisiae (NP_015346)

2.A.29.14.5 solute carrier family 25 (glutamate carrier), member 18AnimalsSLC25A18 of Homo sapiens

solute carrier family 25, member 40.  This mitochondrial inner membrane transporter can be mutated (Y125C) to give hypertriglyceridemia (Rosenthal et al. 2013).  May also be involved in  primary Sjögren's syndrome (pSS), a prevalent and disabling form of fatigue (Norheim et al. 2014).


SLC25A40 of Homo sapiens

2.A.29.14.7 solute carrier family 25, member 44AnimalsSLC25A44 of Homo sapiens
2.A.29.14.8Solute carrier family 25 member 39AnimalsSLC25A39 of Homo sapiens

MC family homologue of 327 aas and 6 TMSs


MCP homologue of Ostreococcus lucimarinus


TC#NameOrganismal TypeExample
2.A.29.15.1Oxaloacetate/malonate/sulfate/thiosulfate transporter, OAC1 Yeast Oxaloacetate carrier (OAC1) of Saccharomyces cerevisiae
2.A.29.15.2 solute carrier family 25, member 35AnimalsSLC25A35 of Homo sapiens
2.A.29.15.3 solute carrier family 25, member 34AnimalsSLC25A34 of Homo sapiens

TC#NameOrganismal TypeExample

Reported to be a deoxynucleotide (enzyme), the deoxynucleotide carrier (DNT) (all four dNDPs and less efficiently, all four dNTPs are transported, but not dNMPs, NMPs or nucleosides). It is also a thiamin pyrophosphate (TPP) transporter responsible for Amish lethal microencephaly brain development retardation (MCPHA) and α-ketoglutarate acidurua when defective (Arco and Satrústegui, 2005; Lindhurst et al., 2006; Iacopetta et al., 2010).

AnimalsSLC25A19 of Homo sapiens

The thiamin pyrophosphate (TPP) transporter, Tpc1; catalyzes thiamin pyrophosphate/thiamin monophosphate excange (Palmieri et al. 2006).  Also transports pyrophosphate, ADP, ATP and other nucleotides (Iacopetta et al., 2010).


Tpc1 of Drosophila melanogaster (Q7K0L7)

2.A.29.16.3Uncharacterized mitochondrial carrier C1604.04YeastSPBC1604.04 of Schizosaccharomyces pombe

TC#NameOrganismal TypeExample

Peroxisomal ATP/ADP/AMP antiporter, Ant1 (Ypr128cp) (Palmieri et al. 2006).


Ant1 of Saccharomyces cerevisiae (AAB68270)


TC#NameOrganismal TypeExample

Mitochondrial S-adenosylmethionine (SAM) carrier, Sam5p or PET8 (Marobbio et al., 2003).  Catalyzes the exchange of SAM for S-adenosylhomoserine as well as biotin and lipoate transport (Palmieri et al. 2006).


Sam5p of Saccharomyces cerevisiae (P38921)


The plastid S-Adenosylmethionine importer, SAMT1 (regulates plastid biogenesis and plant development; catalyzes the counter-exchange of SAM with SAM and with S-adenosylhomocysteine) (Bouvier et al., 2006).  Also present in the mitochondrion (Haferkamp and Schmitz-Esser 2012).


SAMT1 of Arabidopsis thaliana (Q94AG6)

2.A.29.18.3 solute carrier family 25 (S-adenosylmethionine carrier), member 26AnimalsSLC25A26 of Homo sapiens

Uncharacterized protein of 369 aas and 6 TMSs

UP of Chlamydomonas reinhardtii (Chlamydomonas smithii)


TC#NameOrganismal TypeExample

Mitochondrial ornithine carrier 2 (ORC2 or OrnT2) (transports ornithine, citrulline, lysine, arginine, histidine); HHH syndrome (SLC25A2). Catalyzes ornithine:citrulline antiport and ornithine:H+ antiport (Tonazzi and Indiveri, 2011).

AnimalsSLC25A2 of Homo sapiens

Mitochondrial ornithine transporter (ornithine/citrulline exchanger), SLC25A15 or Orc1. Catalyzes a vital step in the urea cycle, interconnecting the cytosolic and mitochondrial components for the cycle (Moraes and Reithmeier 2012).


SLC25A15 of Homo sapiens


TC#NameOrganismal TypeExample

Oxoglutarate/malate antiporter. Also transports porphyrin derivatives: Fe-protoporphyrin IX, coproporphyrin III, hemin, etc. (Kabe et al., 2006). Plays roles in the malate-aspartate shuttle, the oxoglutarate-isocitrate shuttle and gluconeogenesis.  Functional residues have been identified (Cappello et al. 2007).


Oxoglutarate/malate carrier of Bos taurus


The dicarboxylate-tricarboxylate carrier (PfDTC) catalyzes oxoglutarate-malate, oxoglutarate-oxaloacetate, or oxoglutarate-oxoglutarate  exchange (Nozawa et al., 2011).


DTC of Plasmodium falciparum (Q8IB73)


solute carrier family 25 (mitochondrial carrier; oxoglutarate/malate carrier), member 11


SLC25A11 of Homo sapiens (Q9CR62)

2.A.29.2.12Solute carrier family 25 member 52 (Mitochondrial carrier triple repeat protein 2)AnimalsSLC25A52 of Homo sapiens
2.A.29.2.13Mitochondrial 2-oxoglutarate/malate carrier protein (OGCP) (Solute carrier family 25 member 11)AnimalsSLC25A11 of Homo sapiens
2.A.29.2.14Solute carrier family 25 member 51 (Mitochondrial carrier triple repeat protein 1)AnimalsSLC25A51 of Homo sapiens
2.A.29.2.2Dicarboxylate (succinate/fumarate/ malate/α-ketoglutarate/ oxaloacetate) antiporter Animals Dicarboxylate transporter of Rattus norvegicus
2.A.29.2.3Dicarboxylate:Pi antiporter (Pi, malate, succinate, oxaloacetate, sulfate, sulfite) Yeast Dicarboxylate:Pi antiporter of Saccharomyces cerevisiae

Mammalian oxodicarboxylate carrier (ODC; SLC25A21; 607571) (transports C5-C7 oxodicarboxylates including 2-oxoadipate and 2-oxoglutarate in an antiport reaction; also transports less well: pimelate, 2-oxopimelate, 2-amino adipate, oxaloacetate, and citrate) (Defects cause 2-oxoadipate acidemia, an inborn error of metabolism)


SLC25A21 of Homo sapiens


2-oxodicarboxylate carrier 2 (ODC2) (transports the same substrates as human ODC except that 2-amino adipate is not transported while malate is) (Palmieri et al. 2006).


ODC2 of Saccharomyces cerevisiae (Q99297)

2.A.29.2.6Plant dicarboxylate/tricarboxylate carrier, DTC, transports dicarboxylates (such as malate, oxaloacetate, oxoglutarate, and maleate) and tricarboxylates (such as citrate, isocitrate, cis-aconitate, and trans-aconitate)PlantsDTC of Nicotiana tabacum

Mitochondrial dicarboxylate carrier (DIC; SLC25A10; 606794) transports malate, succinate, phosphate, sulfate, thiosulfate

AnimalsSLC25A10 of Homo sapiens
2.A.29.2.82-oxodicarboxylate carrier 1 (ODC1) transports C5-C7 oxodicarboxylic acid (2-oxoadipate, 2-oxoglularate, adipate, glutarate, 2-oxopimelate, oxaloacetate, citrate and malate) (functions by a strict antiport mechanism (Palmieri et al., 2001). YeastODC1 of Saccharomyces cerevisiae (Q03028)

The dicarboxylate carriers, DIC1 (transports malate, oxaloacetate and succinate as well as phosphate, sulfate and thiosulfate at high rates: 2-oxoglutarate is a poor substrate (Palmieri et al., 2007)).


DIC1 of Arabidopsis thaliana (Q9SJY5)


TC#NameOrganismal TypeExample

Peroxisomal adenine nucleotide carrier, PMP34 (ANC; SLC25A17).  Probably specific for multiple cofactors like coenzyme A (CoA), flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN) and nucleotide adenosine monophosphate (AMP), and to a lesser extend for nicotinamide adenine dinucleotide (NAD+), adenosine diphosphate (ADP) and adenosine 3',5'-diphosphate (PAP). May catalyze the transport of free CoA, FAD and NAD+ from the cytosol into the peroxisomal matrix by a counter-exchange mechanism. Inhibited by pyridoxal 5'-phosphate and bathophenanthroline in vitro (Visser et al. 2002; Agrimi et al. 2012).


SLC25A17 of Homo sapiens


Peroxisomal adenine nucleotide carrier 2, PNC2.  Transports ATP, ADP and NAD+ (Linka and Esser 2012).



PNC2 of Arabidopsis thaliana


Peroxisomal nucleotide (ATP, ADP, AMP) carrier-1, PNC1 (Haferkamp and Schmitz-Esser 2012).


PNC1 of Arabidopsis thaliana


TC#NameOrganismal TypeExample

Mitochondrial GTP/GDP exchange carrier (Ggc1) [also transports deoxyGTP and deoxyGDP as well as ITP and IDP but less well than GTP and GDP] [KM(GTP)=1 μM; KM(GDP)=5 μM]. Inhibited by pyridoxal-5-P, bathophenanthroline and tannic acid but not by inhibitors of the ATP-ADP carrier (Vozza et al., 2004). GGC appears to be intrinsically plastic with structural plasticity asymmetrically distributed among the three homologous domains (Sounier et al. 2015).


Ggc1 of Saccharomyces cerevisiae (NP_010083)


TC#NameOrganismal TypeExample
2.A.29.22.1Hydrogenosome ATP/ADP antiporter, HMP31 (Tjaden et al., 2004)Anaerobic flagellatesHMP31 of Trichomonas gallinae (AAP30846)

The Mitosome (crypton) ADP/ATP carrier (Chan et al., 2005)


Mitosome ADP/ATP carrier of Entamoeba histolytica (AAK69775)


TC#NameOrganismal TypeExample
2.A.29.23.1Mitochondrial ATP-Mg2+/inorganic phosphate antiporter [3 isoforms in humans with 3 EF-hand CA2+ binding motifs in their N-terminal domain: Q6KCM7, Q9BV35, and Q6NUK1] (Fiermonte et al., 2004)AnimalsSLC25A25 of Homo sapiens
2.A.29.23.2Mg2+-ATP/Pi carrier, Sal1 (Ca2+ binding carrier, CMC1; supressor of AAC2 lethality (EF hand Ca2+ binding motif at N-terminus). ADP:ATP carrier 2 (Kucejova et al., 2008; Traba et al., 2008)YeastSal1 of Saccharomyces cerevisiae (P48233)

Chloroplast thylakoid ATP/ADP antiporter, TAAC (Thuswaldner et al., 2007; Haferkamp et al., 2011).  Also transports 3'-phosphoadenosine 5'-phosphosulfate (PAPS), made in the mitochondria and exported to the cytoplasm where it is involved in several aspects of sulfur metabolism, including the biosynthesis of thiols, glucosinolates, and phytosulfokines, and therefore also named PAPST1 (Gigolashvili et al. 2012).  Expression of the PAPST1 gene is regulated by the same MYB transcription factors that also regulate the biosynthesis of sulfated secondary metabolites, glucosinolates.


TAAC of Arabidopsis thaliana (Q9M024)

2.A.29.23.4The mitochondrial adenine nucleotide transporter, ADNT1 (At4g01100) (prefers AMP and ADP to ATP; not inhibited by bongkrekate or carboxyatractyloside; loss yields reduced root growth and respiration) (Palmieri et al., 2008b).


ADNT1 of Arabidopsis thaliana (O04619)

2.A.29.23.5 solute carrier family 25 (mitochondrial carrier; phosphate carrier), member 23AnimalsSLC25A23 of Homo sapiens
2.A.29.23.6 solute carrier family 25, member 41AnimalsSLC25A41 of Homo sapiens

solute carrier family 25, member 43.  May play a role in Paget's bone disease (Gutiérrez-Aguilar and Baines 2013).  Also regulates cell cycle progression and proliferation through a putative mitochondrial checkpoint (Gabrielson et al. 2015).


SLC25A43 of Homo sapiens


Calcium-binding mitochondrial carrier protein SCaMC-1 (Mitochondrial ATP-Mg/Pi carrier protein 1; Mitochondrial Ca2+-dependent solute carrier protein 1; Small calcium-binding mitochondrial carrier protein 1; Solute carrier family 25 member 24).  The crystal structure of the N-terminal Ca2+-binding domain has been determined and shown to undergo a large conformational change when Ca2+ binds (Yang et al. 2014).


SLC25A24 of Homo sapiens


Mitochondrial transporter for 3′-phospho-adenosine 5′-phosphosulfate and adenosine 5′-phosphosulfate (APS), YPR011c.  Sulfate and phosphate are also transported using an antiport mechanism (Todisco et al. 2014).  Inhibited by bongkrekic acid.  Deletion mutants are thermal sensitive and have less methionine and glutathione.  The gene is induced by thermal stress conditions (Todisco et al. 2014).


YPR011c of Saccharomyces cerevisiae


TC#NameOrganismal TypeExample

Brain mitochondrial carrier protein 1, BMCP1 (participates in mitochondrial proton leak) (also called uncoupling protein-5 (UCP5)) (Sanchis et al., 1998).  Transports protons and chloride ions; activated by fatty acids and inhibited by purine nucleotides similarly to UCP1-3 (Hoang et al. 2012); H+ transport may be activated while Cl- transport may be inhibited by faty acids (Hoang et al. 2015). 


SLC25A14 of Homo sapiens

2.A.29.24.2Kidney mitochondrial carrier protein, KMCP1 (Haguenauer et al., 2005) AnimalsKMCP1 of Mus musculus (NP_080508)

solute carrier family 25, member 27; UCP4.  Transports protons and chloride ions; activated by fatty acids and inhibited by purine nucleotides similarly to UCP1-3 (Hoang et al. 2012).  H+ transport may be activated while Cl- transport may be inhibited by fatty acids (Hoang et al. 2015).


SLC25A27 of Homo sapiens


solute carrier family 25, member 30; Kidney MCP1

AnimalsSLC25A30 of Homo sapiens

TC#NameOrganismal TypeExample

The mitochondrial presenilin-associated protein (PSAP; MTCH1) binds to the PDZ domain (a QFYI motif) C-terminus of presenilin. It contains 2 solcar repeats and is 389 aas long. It is most similar to 2.A.29.23.1 and 2.A.29.12.1. There are 2 human isoforms, mitochondrial carrier homologues, MTCH1 and MTCH2, possibly involved in apoptosis (Xu et al., 1999, 2002). Its transport function is unknown (Xu et al., 1999, 2002).  Surprisingly, this protein has been reported to be targetted to the outer mitochonrdial membrane (Gutiérrez-Aguilar and Baines 2013). Two proapoptotic PSAP isoforms generated by alternative splicing differ in the length of a hydrophilic loop located between two predicted transmembrane domains. Both isoforms are expressed in human and rat tissues. PSAP probably contains multiple mitochondrial targeting motifs dispersed along the protein (Lamarca et al. 2007).


MTCH1 of Homo sapiens (Q9NZJ7)


The mitochondrial carrier homologue-2 (MTCH2). Binds the BH3-interacting domain death agonist, BID. Regulated (induced) by the hepatocyte growth factor receptor, HGF/SF or Met. It has been proposed that its transport function has been lost (Robinson et al., 2012). Surprisingly, this protein has been reported to be targetted to the outer mitochondrial membrane (Gutiérrez-Aguilar and Baines, 2013).


MTCH2 of Homo sapiens (Q9Y6C9)


TC#NameOrganismal TypeExample

Viral mitochondrial carrier-like protein, L276 (VMC) for dATP and dTTP (237 aas) (Monné et al., 2007).

Animal virus

VMC of Mimiviridae mimivirus (Q5UPV8)


TC#NameOrganismal TypeExample

The ATP exchanger/symporter, LcnP (secreted via the bacterial Dot/Icm type IV secretion system into macrophages, and assembled in the mitochondrial inner membrane (Dolezal et al., 2012)).


LcnP of Legionella pneumophila (Q5WSP6)


TC#NameOrganismal TypeExample
2.A.29.28.1The thiamin pyrophosphate (TPP) carrier, TPC1 (Marobbio et al., 2002).YeastTPC1 of Saccharomyces cerevisiae (NP_011610)

TC#NameOrganismal TypeExample

The citrate/oxoglutarate carrier, Yhm2 (Castegna et al., 2010; Mayor et al., 1997). Ymh2 also transports oxaloacetate, succinate, and fumarate, but not malate or isocitrate. It may function in antioxidation (Castegna et al., 2010).


Yhm2 of Saccharomyces cerevisiae (Q04013)


TC#NameOrganismal TypeExample
2.A.29.3.1Uncoupling protein (H+; halide anions; protonated or anionic fatty acids) Animals Uncoupling carrier of Bos taurus

Mitochondrial brown fat uncoupling protein 1 (UCP1) (thermogenin); obesity protein (SLC25A7); mediates adaptive thermogenesis Azzu and Brand, 2009).  Transports protons and chloride ions; activated by fatty acids and inhibited by purine nucleotides (Hoang et al. 2012).  Functions as a long-chain fatty acid (LCFA) anion/H+ symporter, but the LCFA anion can don dissociatedue to hydrophobic interactions, so it is, in effect, an H+ carrier (Fedorenko et al. 2012).  Thermogenic Brown adipose tissue cells with increased UCP1 activity also have increased ATP sythase activity to allow maintenance of normal ATP levels (Guillen et al. 2013).


UCP1 of Homo sapiens


The uncoupling protein, UCP1 or PUMP (functions to relieve oxidative stress, and to allow efficient photosynthesis (Sweetlove et al., 2006).  In spome plants, it is activated in response to cold stress and may control reactive oxygen species (Valente et al. 2012).


UCP1 of Arabidopsis thaliana


Human UCP2; implicated in a variety of physiological and pathological processes including protection from oxidative stress, negative regulation of glucose sensing systems and the adaptation of fatty acid oxidation capacity to starvation. Not involved in thermogenesis as is UCP1 (Azzu and Brand, 2009). Leucine zipper EF hand-containing transmembrane protein 1 (LetM1; 2.A.97) and uncoupling proteins 2 and 3 (UCP2/3) contribute to two distinct mitochondrial Ca2+ uptake pathways (Waldeck-Weiermair et al., 2011).  Transports protons and chloride ions; activated by fatty acids and inhibited by purine nucleotides (Hoang et al. 2012).  Reduces mitochondrial Ca2+ uptake in response to intracellular Ca2+ release in pancreatic beta cells (Alam et al. 2012).  Arginine residues in TMS2 are important for chloride transport without affecting fatty acid-dependent proton transport (Hoang et al. 2015).


UCP2 of Homo sapiens


Human UCP3; implicated in a variety of physiological and pathological processes including protection from oxidative stress, negative regulation of glucose sensing systems and the adaptation of fatty acid oxidation capacity to starving. Not involved in thermogenesis as is UCP1 (Azzu and Brand, 2009). It also modulates the activity of the sarco/endoplasmic reticulum Ca2 -ATPase (SERCA) by decreasing mitochondrial ATP production (De Marchi et al., 2011). Leucine zipper EF hand-containing transmembrane protein 1 (LetM1; 2.A.97) and uncoupling proteins 2 and 3 (UCP2/3) contribute to two distinct mitochondrial Ca2 uptake pathways (Waldeck-Weiermair et al., 2011).  Transports protons and chloride ions; activated by fatty acids and inhibited by purine nucleotides (Hoang et al. 2012).

AnimalsUCP3 of Homo sapiens

Uncouopling protein B, UCPB, of 268 aas and 5 TMSs, with TMS 5 deleted.  This protein can still function as an uncoupling protein (Ito et al. 2006).

UCPB of Symplocarpus renifolius


Uncoupling protein A (UCPA) of 303 aas and 6 TMSs.  Functions as an uncoupling protein, transporting protons across the mitochondrial inner membrane (Ito et al. 2006).

UCPA of Symplocarpus renifolius (skunk cabbage)


TC#NameOrganismal TypeExample

The human mitochondrial carrier (418aas; 6 TMSs) of unknown function (SLC25A46).  May play a role in atopic dermatitis (Gutiérrez-Aguilar and Baines 2013).


SLC25A46 of Homo sapiens


TC#NameOrganismal TypeExample

Sequence-divergent mitochondrial carrier of 394 aas and 6 TMSs, MCP14.  The T. brucei MCP14 appears to be involved in energy metabolism but it also mediates drug action and is required for cell growth and viability (de Macêdo et al. 2015).  TbMCP14 belongs to a trypanosomatid-specific clade of the mitochondrial carrier family.


MCP14 of Trypanosoma cruzi


MCP14 orthologue of 447 aas and 6 TMSs


MCP14 of Leishmania major


MCP14 paralogue of 361 aas and 6 TMSs


MCP14 of Trypanosoma cruzi


MCP14 homologue of 338 aas and 6 TMSs.


MCP14 homologue of Strigomonas culicis


TC#NameOrganismal TypeExample
2.A.29.4.1Phosphate carrier Animals, yeast Phosphate carrier of Bos taurus

Phosphate carrier protein (PiC); mitochondrial precursor (PTP) (SLC25A3).  Variants lead to a failure of inorganic phosphate (Pi) transport across the mitochondrial membrane, loss of oxidative phosphorylation, and phenotypically varied cases of skeletal myopathy and cardiomyopathy (Bhoj et al. 2015).


SLC25A3 of Homo sapiens


Phosphate carrier, Pic1: (PTP1; Mir1) (Hamel et al., 2004).  Also transports short chain (methane) phosphonates and medium chain (C12, C14 and C16) fatty acids which competitively inhibit phosphate transport (Engstová et al. 2001).


Pic1 of Saccharomyces cerevisiae (P23641)

2.A.29.4.4Phosphate carrier, Pic2: (PTP2; functionally equivalent paralogue of Pic1) (Hamel et al., 2004)


Pic2 of Saccharomyces cerevisiae (P40035)


solute carrier family 25 (mitochondrial carrier; phosphate carrier), member 3


Phosphate carrier of Mus musculus (Q8VEM8)


Mitochondrial phosphate carrier-1, PiC1, AT5, PHT3;1 of 375 aas and 6 TMSs (Liu et al. 2017).


PiC1 of Arabidopsis thaliana


TC#NameOrganismal TypeExample
2.A.29.5.1MRS3 iron (Fe2+) import carrier in the inner mitochondrial membrane; essential for erythroid iron utilization) (Mühlenhoff et al., 2003). Uptake is dependent on the pH gradient (Froschauer et al. 2009).


MRS3 of Saccharomyces cerevisiae

2.A.29.5.2MRS4 iron (Fe2+) import carrier in the inner mitochondrial membrane; essential for erythroid iron utilization) (Mühlenhoff et al., 2003). Uptake is dependent on the pH gradient (Froschauer et al. 2009).


MRS4 of Saccharomyces cerevisiae


Mitochondrial iron transporter, mitoferrin (Shaw et al., 2006). Essential for erythroid iron utilization (Froschauer et al. 2009). Mitochondrial iron import regulation occurs through differential turnover of mitoferrin 1 and mitoferrin 2 (Paradkar et al., 2009)


Mitoferrin of Brachydanio rerio (Q287T7)


solute carrier family 25 (mitochondrial iron transporter), member 28, putative iron transporter; Mitoferrin-2


Mitoferrin-2 of Mus musculus (Q8R0Z5)


solute carrier family 25 (mitochondrial iron transporter), member 37, putative iron transporter, Mitoferrin-1


Mitoferrin-1 of Mus musculus (Q920G8)


Solute carrier family 25, member 38, SLC25A38; probably involved in heme biosynthesis by importing glycine and/or 5-aminolevulinate into mitochondria (Gutiérrez-Aguilar and Baines 2013).


SLC25A38 of Homo sapiens

2.A.29.5.7Mitoferrin-1 (Mitochondrial iron transporter 1) (Mitochondrial solute carrier protein) (Solute carrier family 25 member 37)AnimalsSLC25A37 of Homo sapiens

Mitoferrin-2 (Mitochondrial RNA-splicing protein 3/4 homologue) (MRS3/4) (hMRS3/4) (Mitochondrial iron transporter 2) (Solute carrier family 25 member 28)


SLC25A28 of Homo sapiens


TC#NameOrganismal TypeExample

Peroxisomal carrier, PMP47. May be a transporter for several enzyme cofactors (based on similarity to human PMP34 (TC# 2.A.29.20.1)


PMP47 of Candida boidinii


Peroxysomal/glyoxysomal PMP38 (PXN) of 331 aas. Mediates NAD import into peroxisomes. Favors NAD (in)/AMP(out) antiport, but can also catalyze unidirectional transport that might be essential under special conditions. Transports CoA, dephospho-CoA, acetyl-CoA, adenosine 3'',5''-diphosphate (PAP), NAD , AMP, ADP and NADH, but not ATP, GTP, GDP, NADPH, NADP or FAD. Required for peroxisomeal proliferation (Mano et al. 2011; Agrimi et al. 2012; Bernhardt et al. 2012).


PMP38 of Arabidopsis thaliana


TC#NameOrganismal TypeExample
2.A.29.7.1Tricarboxylate carrier (exchanges a tricarboxylate (citrate, isocitrate, cis-aconitate) + H+ for another tricarboxylate + H+, a dicarboxylate (malate, succinate) or phosphoenolpyruvate). Animals Citrate carrier of Rattus norvegicus

Citrate/malate exchange carrier CIC (CTP); tricarboxylate carrier (citrate·H+/malate, PEP) (SLC25A1)


SLC25A1 of Homo sapiens


Citrate transport protein, CTP1. Catalyzes obligatory exchange of the dibasic form of tricarboxylates (citrate and isocitrate) for other tricarboxylates. Two citrate binding sites per monomer have been identified (Ma et al., 2007). Mutations in residues in internal or external pore regions can relax the specificity, converting CTP1 into a nonspecific anion carrier. The data is consistent with outward-facing, occluded, and inward-facing states.


CTP1 of Saccharomyces cerevisiae (P38152)

2.A.29.7.4The fruit fly citrate uptake carrier, CIC (expressed at all stages of development; same substrate as for other eukaryotic tricarboxylate transporters (Carrisi et al., 2008).


CIC of Drosophila melanogaster (Q7KSQ0)


The citrate carrier (CIC) (Madeo et al., 2009)


CIC of Anguilla anguilla (Q1ENH3)


TC#NameOrganismal TypeExample
2.A.29.8.1Mitochondrial carnitine/acyl carnitine carrier (CAC) Mammals CAC of Rattus norvegicus
2.A.29.8.10Solute carrier family 25 member 47 (Hepatocellular carcinoma down-regulated mitochondrial carrier protein)AnimalsSLC25A47 of Homo sapiens
2.A.29.8.11Carrier protein YMC2, mitochondrialFungiYMC2 of Saccharomyces cerevisiae
2.A.29.8.12Carrier protein YMC1, mitochondrialFungiYMC1 of Saccharomyces cerevisiae

Basic amino acid carrier2, BAC2 of 296 aas and 6 TMSs.  This hyperosmotic stress-inducible porter transports proline in addition to basic amino acids (Toka et al. 2010).


BAC2 of Arabidopsis thaliana


Low-CO2-inducible chloroplast envelope protein, Ccp1, of 358 aas and 6 or 7 TMSs. Probabe HCO3- concentrating transporter (Atkinson et al. 2016).  May be present in mitochondria rather than chloroplasts.  Ccp2 (O24451) is 96% identical to Ccp1.

Ccp1 of Chlamydomonas reinhardtii (Chlamydomonas smithii)

2.A.29.8.2Embryonic differentiation (DIF-1) protein Animals DIF-1 of Caenorhabditis elegans

Human mitochondrial carnitine/acyl carnitine carrier; carnitine/acyl carnitine translocase (CACT). Defects in CACT (SLC25A20) cause CACT deficiency [MIM212138] (autosomal recessive; lethal) (Indiveri et al., 2011).


SLC25A20 of Homo sapiens


Carnitine carrier, CRC1.  Exchanges carnitine for acetylcarnitine (Palmieri et al. 2006).


CRC1 of Saccharomyces cerevisiae (Q12289)

2.A.29.8.5The carnitine:acylcarnitine exchange translocase, CACL. CACL is similar in tissue distribution to that of CACT (TC# 2.A.29.8.3); both are expressed at a higher level in tissues using fatty acids as fuels, except the brain, where only CACL is expressed (Sekoguchi et al., 2003) Animals CACL of Homo sapiens (Q8BL03)
2.A.29.8.6The mitochondrial basic amino acid transporter, in mBAC1 (transports the basic L-amino acids arginine, lysine, ornithine, and histidine in order of decreasing affinity; does not transport citrulline; expressed in stems, leaves, flowers, siliques, and seedlings; Km for arg=0.2mM) (Hoyos et al., 2003)PlantsmBAC1 of Arabidopsis thaliana (Q84UC7)
2.A.29.8.7 solute carrier family 25, member 45AnimalsSLC25A45 of Homo sapiens

solute carrier family 25, member 48.  May be associated with Parkinson's disease (Gutiérrez-Aguilar and Baines 2013).


SLC25A48 of Homo sapiens


Mitochondrial carrier protein CACL (CACT-like) (Solute carrier family 25 member 29).  Transports basic amino acids (Porcelli et al. 2014).  It transports arginine, lysine, homoarginine, methylarginine and, to a much lesser extent, ornithine and histidine. Carnitine and acylcarnitines were not transported by SLC25A29. This carrier catalyzes substantial uniport besides counter-exchange transport and exhibits a high transport affinity for arginine and lysine.  It is saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. The main physiological role of SLC25A29 is to import basic amino acids into mitochondria for mitochondrial protein synthesis and amino acid degradation (Porcelli et al. 2014).


SLC25A29 of Homo sapiens


TC#NameOrganismal TypeExample
2.A.29.9.1Mitochondrial basic amino acid carrier (BAAC) Fungi BAAC of Neurospora crassa

Ornithine/arginine carrier, ORT1 or ARG11 (Palmieri et al., 1997).  Catalyzes H+:ornithine antiport for the export of ornithine from mitochondria (Palmieri et al. 2006).


ORT1 of Saccharomyces cerevisiae (Q12375)


Uncharacterized protein of 416 aas and 6 - 7 TMSs, MITC1.

MITC1 of Chlamydomonas reinhardtii (Chlamydomonas smithii)