TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
2.A.3.1:  The Amino Acid Transporter (AAT) Family
*2.A.3.1.1









Phenylalanine:H+ symporter, PheP of 458 aas and 12 established TMSs (Pi and Pittard 1996; Pi et al. 2002).  Catalytic residues have been identified (Pi et al. 1993), and interhelical interactions have been proposed (Dogovski et al. 2003).

Bacteria
Proteobacteria
PheP of E. coli
*2.A.3.1.2









Lysine:H+ symporter. Forms a stable complex with CadC to allow lysine-dependent adaptation to acidic stress (Rauschmeier et al. 2013). The Salmonella orthologue is 95% identical to the E. coli protein and is highly specific for Lysine. Residues involved in lysine binding have been identified (Kaur et al. 2014).

Bacteria
Proteobacteria
LysP of E. coli
*2.A.3.1.3









Aromatic amino acid:H+ symporter, AroP of 457 aas and 12 TMSs (Cosgriff and Pittard 1997). Transports phenylalanine, tyrosine and tryptophan (Honoré and Cole 1990).

Bacteria
Proteobacteria
AroP of E. coli
*2.A.3.1.4









γ-aminobutyrate:H+ symporter (also transports a variety of pyridine carboxylates)
Bacteria
Proteobacteria
GabP of E. coli
*2.A.3.1.5









β-alanine/γ-aminobutyrate/proline/3,4-dehydroproline:H+ symporter, GabP (Ferson et al. 1996; Zaprasis et al. 2014).  Also transports 3-aminobutyrate, 3-aminopropanoate, cis-4-aminobutenoate (Brechtel and King 1998).

Bacteria
Firmicutes
GabP of Bacillus subtilis
*2.A.3.1.6









Proline-specific permease (ProY)
Bacteria
Proteobacteria
ProY of Salmonella typhimurium
*2.A.3.1.7









D-Serine/D-alanine/glycine/D-cycloserine:H+ symporter (regulated by the small RNA, GcvB; Pulvermacher et al., 2009).  The system is active after growth in minimal medium but not after growth in complex medium (Baisa et al. 2013).

Bacteria
Proteobacteria
CycA of E. coli (P0AAE0)
*2.A.3.1.8









Asparagine permease (AnsP) of 497 aas and 12 TMSs (Jennings et al. 1995).

Bacteria
Proteobacteria
AnsP of Salmonella typhimurium
*2.A.3.1.9









Histidine permease HutT
Bacteria
Proteobacteria
HutT of Pseudomonas putida
*2.A.3.1.10









S-Methylmethionine permease, MmuP
Bacteria
Proteobacteria
MmuP of E. coli
*2.A.3.1.11









L-Arginine permease, RocE
Bacteria
Firmicutes
RocE of Bacillus subtilis
*2.A.3.1.12









Aromatic amino acid permease, AroP (Wehrmann et al., 1995)
Bacteria
Actinobacteria
AroP of Corynebacterium glutamicum (Q46065)
*2.A.3.1.13









Putrescine importer, PuuP (Kurihara et al., 2005)
Bacteria
Proteobacteria
PuuP of E. coli (P76037)
*2.A.3.1.14









Low-affinity putrescine importer PlaP
Bacteria
Proteobacteria
PlaP of Escherichia coli
*2.A.3.1.15









Probable transport protein YifK
Bacteria
Proteobacteria
YifK of Escherichia coli
*2.A.3.1.16









Uncharacterized transporter YdgF
Bacteria
Firmicutes
YdgF of Bacillus subtilis (P96704)
*2.A.3.1.17









D-serine/L-alanine/D-alanine/glycine/D-cycloserine uptake porter of 556 aas, CycA.  Can be mutated to D-cycloserine (a seconary line antitubercular drug) resistance (Chen et al. 2012).

Bacteria
Actinobacteria
CycA of Mycobacterium bovis
*2.A.3.1.18









The lysine specific transporter, LysP of 488 aas and 12 TMSs (Trip et al. 2013).

Bacteria
Firmicutes
LysP of Lactococcus lactis
*2.A.3.1.19









Transporter of lysine, histidine and arginine, HisP or LysQ, of 477 aas and 12 TMSs (Trip et al. 2013).

Bacteria
Firmicutes
LysQ (HisP) of Lactococcus lactis
*2.A.3.1.20









Serine transporter, SerP2 or YdgB, of 459 aas and 12 TMSs (Trip et al. 2013). Transports L-alanine (Km = 20 μM), D-alanine (Km = 38 μM), L-serine, D-serine (Km = 356 μM) and glycine (Noens and Lolkema 2015). The encoding gene is adjacent to the one encoding SerP1 (TC# 2.A.3.1.21).

Bacteria
Firmicutes
SerP2 of Lactococcus lactis
*2.A.3.1.21









Serine uptake transporter, SerP1, of 259 aas and 12 TMSs (Trip et al. 2013). L-serine is the highest affinity substrate (Km = 18 μM), but SerP1 also transports L-threonine and L-cysteine (Km values = 20 - 40 μM).  Does not transport D-serine (Noens and Lolkema 2015). The encoding gene is adjacent to a paralogue (serP2) with broad specificity for D- and L-small semipolar amino acids and glycine (see TC# 2.A.3.1.20).

Bacteria
Firmicutes
SerP1 of Lactococcus lactis
*2.A.3.1.22









Transporter for phenylalainine, tyrosine and tryptophan of 449 aas and 12 TMSs, FywP or YsjA (Trip et al. 2013).

Bacteria
Firmicutes
FywP of Lactococcus lactis
*2.A.3.1.23









ProY of 457 aas and 12 TMSs.  96% identical to ProY of Salmonella enterica, a cryptic proline transporter in this organism (Liao et al. 1997).

Bacteria
Proteobacteria
ProY of E. coli
*2.A.3.1.24









Asparagine transporter of 499 aas and 12 TMSs, 91% identical to the orthologue in Salmonella enterica (2.A.3.1.8) (Jennings et al. 1995).

Bacteria
Proteobacteria
AnsP of E. coli
2.A.3.2:  The Basic Amino Acid/Polyamine Antiporter (APA) Family
*2.A.3.2.1









Putrescine:ornithine antiporter for putrescine export; putrescine:H+ symporter for uptake (Igarashi and Kashiwagi 1996). Modeling tools have been used to gain information about the structures and functions of CadB and PotE in E. coli (Tomitori et al., 2012).

Bacteria
Proteobacteria
PotE of E. coli (P0AAF1)
*2.A.3.2.2









Cadaverine:lysine antiporter [Catalyzes cadaverine uptake via H+ symport (Km=21μM) and cadaverine export (Km=300 μM) via cadaverine:lysine antiport.] (Soksawatmaekhin et al., 2004). Modeling tools have been used to gain information about the structures and functions of CadB and PotE in E. coli (Tomitori et al., 2012).

Bacteria
Proteobacteria
CadB of E. coli (P0AAE8)
*2.A.3.2.3









Arginine:ornithine antiporter
Bacteria
Proteobacteria
ArcD of Pseudomonas aeruginosa
*2.A.3.2.4









Lysine permease
Bacteria
Actinobacteria
LysI of Corynebacterium glutamicum
*2.A.3.2.5









Homodimeric electrogenic arginine (Km=80μM):agmatine antiporter, AdiC, involved in extreme acid resistance (Fang et al., 2007; Gong et al., 2003; Iyer et al., 2003). A projection structure at 6.5 Å resolution has been published (Casagrande et al., 2008), and the 3.2 Å resolution X-ray structure was determined by Fang et al., 2009 and Gao et al., 2009. Protonation of glutamate 208 induces release of agmatine in the outward-facing conformation (Zomot and Bahar, 2011). The 3.0 Å structure of an Arg-bound form in an open-to-out conformation completed the picture of the major states of the porter during the transport cycle (Kowalczyk et al., 2011). Aromatic residues may regulate access to both the outward- and inward-facing states (Krammer et al. 2016).

Bacteria
Proteobacteria
YjdE (AdiC) of E. coli (P39269)
*2.A.3.2.6









Putative lysine uptake permease, YvsH (Rodionov et al., 2003)
Bacteria
Firmicutes
YvsH of Bacillus subtilis (CAA11718)
*2.A.3.2.7









Arginine/agmatine antiporter
Bacteria
Chlamydiae/Verrucomicrobia group
AaxC of Chlamydia pneumoniae
*2.A.3.2.8









Putative arginine/ornithine antiporter
Bacteria
Proteobacteria
YdgI of Escherichia coli
*2.A.3.2.9









The histidine/histamine antiporter, HdcP of 490 aas and 13 TMSs (Trip et al. 2013).

Bacteria
Firmicutes
HdcP of Streptococcus thermophilus
*2.A.3.2.10









Arginine/Ornithine antiporter of 497 aas and 13 TMSs, ArcD2 (Trip et al. 2013).

Bacteria
Firmicutes
ArcD2 of Lactococcus lactis
*2.A.3.2.11









Arginine/Ornithine antiporter of 526 aas and 14 TMSs (Trip et al. 2013).

Bacteria
Firmicutes
ArcD1 of Lactococcus lactis
2.A.3.3:  The Cationic Amino Acid Transporter (CAT) Family
*2.A.3.3.1









System Y+ high affinity basic amino acid transporter (CAT1) (ecotropic retrovival leukemia virus receptor (ERR)) (transports arginine, lysine and ornithine; Na+-independent)
Eukaryota
Metazoa
CAT1(ERR) of Mus musculus
*2.A.3.3.2









Low affinity basic amino acid transporter (CAT2) (T-cell early activation protein (TEA)) (transports arginine, lysine and ornithine; Na+-independent) (Habermeier et al., 2003)
Eukaryota
Metazoa
CAT2(TEA) of Mus musculus
*2.A.3.3.3









Amino acid transporter, AAT1
Eukaryota
Viridiplantae
AAP1 of Arabidopsis thaliana
*2.A.3.3.4









The amino acid transporter, CAT6. Mediates electrogenic transport of large neutral and cationic amino acids in preference to other amino acids. Present in lateral root primordia, flowers and seeds (Hammes et al., 2006)
Eukaryota
Viridiplantae
CAT6 of Arabidopsis thaliana (Q9LZ20)
*2.A.3.3.5









The brain L-cationic (Arg, Lys, Orn, 2,4-diamino-n-butyrate) transporter, CAT3 (capacity of trans-stimulation by internal Arg) (Ito and Groudine, 1997)
Eukaryota
Metazoa
CAT3 of Mus musculus (P70423)
*2.A.3.3.6









solute carrier family 7 (orphan transporter), member 4
Eukaryota
Metazoa
SLC7A4 of Homo sapiens
*2.A.3.3.7









solute carrier family 7 (orphan transporter), member 14
Eukaryota
Metazoa
SLC7A14 of Homo sapiens
*2.A.3.3.8









Low affinity cationic amino acid transporter 2 (CAT-2) (CAT2) (Solute carrier family 7 member 2) (Closs 1996).

Eukaryota
Metazoa
SLC7A2 of Homo sapiens
*2.A.3.3.9









High affinity cationic amino acid transporter 1 (CAT-1) (CAT1) (Ecotropic retroviral leukemia receptor homologue) (Ecotropic retrovirus receptor homologue) (ERR) (Solute carrier family 7 member 1) (System Y+ basic amino acid transporter) (Closs 1996).

Eukaryota
Metazoa
SLC7A1 of Homo sapiens
*2.A.3.3.10









Cationic amino acid transporter 3 (CAT-3) (CAT3) (Cationic amino acid transporter y+) (Solute carrier family 7 member 3)
Eukaryota
Metazoa
SLC7A3 of Homo sapiens
*2.A.3.3.11









Cationic amino acid transporter 8, vacuolar
Eukaryota
Viridiplantae
CAT8 of Arabidopsis thaliana
*2.A.3.3.12









Cationic amino acid transporter 5
Eukaryota
Viridiplantae
CAT5 of Arabidopsis thaliana
*2.A.3.3.13









Cationic amino acid transporter 2, vacuolar
Eukaryota
Viridiplantae
CAT2 of Arabidopsis thaliana
*2.A.3.3.14









Cationic amino acid transporter 4, vacuolar
Eukaryota
Viridiplantae
CAT4 of Arabidopsis thaliana
*2.A.3.3.15









Uncharacterized protein MG225
Bacteria
Tenericutes
MG225 of Mycoplasma genitalium
*2.A.3.3.16









Uncharacterized amino acid transporter

Bacteria
Actinobacteria
Uncharacterized permease of Streptomyces coelicolor
*2.A.3.3.17









Uncharacterized APC-3 family member

Bacteria
Actinobacteria
U-APC3a of Streptomyces coelicolor
*2.A.3.3.18









Uncharacterized transporter

Bacteria
Proteobacteria
Uncharacterized transporter of Myxococcus xanthus
*2.A.3.3.19









Histamine uptake transporter; involved in the utilization of histamine as a nitrogen source.  In an operon with two histamine catabilic enzymes, and all are induced by hsitamine (Johnson et al. 2008).

Bacteria
Proteobacteria
Histamine uptake transporter of Pseudomonas aeruginosa
*2.A.3.3.20









APC family member of 663 aas and 12 TMSs.

Eukaryota
Peronosporales
APC porter of Phytophthora infestans
*2.A.3.3.21









Uncharacterized protein of 490 aas and 12 TMSs

Bacteria
Firmicutes
UP of Alicyclobacillus acidoterrestris
*2.A.3.3.22









Amino acid transporter, PotE, of 475 aas.

Bacteria
Firmicutes
PotE of Caldanaerobacter subterraneus subsp. tengcongensis (Thermoanaerobacter tengcongensis)
*2.A.3.3.23









Branched chain amino acid (Leucine/isoleucine/valine) uptake transporter of 469 aas and 12 TMSs, BcaP or CitA (den Hengst et al. 2006).

Bacteria
Firmicutes
BcaP (CitA) of Lactococcus lactis
*2.A.3.3.24









Plastidic cationic amino acid transporter, CAT, of 582 aas and 14 TMSs.  Exports phenylalanine, tyrosine and tryptophan our of chloroplasts into the cytoplasm (Widhalm et al. 2015).

Eukaryota
Viridiplantae
CAT of Petunia hybrida
2.A.3.4:  The Amino Acid/Choline Transporter (ACT) Family
*2.A.3.4.1









Choline permease
Eukaryota
Fungi
Ctr (Hnm1) of Saccharomyces cerevisiae
*2.A.3.4.2









γ-aminobutyric acid (GABA) permease, GabA
Eukaryota
Fungi
GabA of Emericella nidulans
*2.A.3.4.3









γ-aminobutyric acid (GABA) permease, Uga4 (also transports the polyamine, putrescine) (Uemura et al., 2007; Kashiwagi and Igarashi 2011).

Eukaryota
Fungi
Uga4 of Saccharomyces cerevisiae (NP_010071)
*2.A.3.4.4









The 7-keto-8-aminopelargonic acid (KAPA) transporter, Bio5 (Phalip et al., 1999).

Eukaryota
Fungi
Bio5 of Saccharomyces cerevisiae (P53744)
*2.A.3.4.5









The polyamine (putrescine > spermidine > spermine) exporter, Tpo5p (Ykl174c) [found in the Golgi or post-Golgi secretory vesicles; induction:spermine > spermidine > putrescine] (Igarashi and Kashiwagi 2010).

Eukaryota
Fungi
Tpo5 of Saccharomyces cerevisiae
*2.A.3.4.6









The thiamine (vitamin B1) transporter, Thi9 (SPAC9.10). Uptake is inhibited by pyrithiamine, oxythiamine, amprolium, and the thiazole part of thiamine indicating that these compounds are substrates of Thi9 (Vogl et al., 2008).

Eukaryota
Fungi
Thi9 of Schizosaccharomyces pombe (Q9UT18)
*2.A.3.4.7









Uncharacterized amino acid transporter

Bacteria
Actinobacteria
Uncharacterized permease of Streptomyces coelicolor
2.A.3.5:  The Ethanolamine Transporter (EAT) Family
*2.A.3.5.1









Ethanolamine import permease
Bacteria
Actinobacteria
Ethanolamine permease of Rhodococcus erythropolis
*2.A.3.5.2









Probable methylamine import permease
Archaea
Euryarchaeota
Methylamine permease of Methanosarcina acetivorans MA0143
2.A.3.6:  The Archaeal/Bacterial Transporter (ABT) Family
*2.A.3.6.1









Putative cationic amino acid permease
Archaea
Euryarchaeota
Cat-1 of Archaeoglobus fulgidus
*2.A.3.6.2









The putative permease, MtbP (MA2426) (possibly a methyl amine uptake porter; D.J. Ferguson, personal communication) (12 putative TMSs)
Archaea
Euryarchaeota
MtbP of Methanoscarina acetivorans (Q8TN67).
*2.A.3.6.3









ApcT, a proton coupled broad specificity amino acid transporter.  3-d structure available at 2.3Å resolution (3GIA_A; Shaffer et al., 2009).

Archaea
Euryarchaeota
ApcT of Methanocaldococcus jannaschii (Q58026)
*2.A.3.6.4









Inner membrane transport protein YbaT
Bacteria
Proteobacteria
YbaT of Escherichia coli
*2.A.3.6.5









Uncharacterized protein MG226
Bacteria
Tenericutes
MG226 of Mycoplasma genitalium
2.A.3.7:  The Glutamate:GABA Antiporter (GGA) Family
*2.A.3.7.1









Glutamate:γ-aminobutyrate antiporter of 477 aas and 12 TMSs, GadC.  Expression of gadCB in L. lactis in the presence of chloride is increased when the culture pH decreases to low levels, while glutamate stimulated gadCB expression (Sanders et al. 1998). These genes encode a glutamate-dependent acid resistance mechanism that is optimally active when needed for acid neutralization.

Bacteria
Firmicutes
GadC of Lactococcus lactis
*2.A.3.7.2









The GadC homologue

Bacteria
Proteobacteria
YcaM of E.coli (P75835)
*2.A.3.7.3









Glutamate:GABA antiporter, GadC (YcaM). GadC, transports GABA/Glu only under acidic conditions, with no detectable activity at pH  values higher than 6.5 (Ma et al., 2012). Ma et al. (2012) determined the crystal structure of GadC at 3.1 Å resolution under basic conditions. GadC, comprising 12 TMSs, exists in a closed state, with its carboxy-terminal domain serving as a plug to block an otherwise inward-open conformation. Structural and biochemical analyses revealed the essential transport residues, identified the transport path and suggested a transport mechanism involving the rigid-body rotation of a helical bundle for GadC and other amino acid antiporters.

Bacteria
Proteobacteria
GadC of E. coli (C8U8G2)
*2.A.3.7.4









Inner membrane transporter, YgjI or GadC. Catalyzes L-glutamate:γ-amino butyrate (GABA) antiport (De Biase and Pennacchietti 2012).

Bacteria
Proteobacteria
YgjI of E. coli
*2.A.3.7.5









Inner membrane transporter, YjeM of 500 aas and 12 TMSs. Probably an amino acid transporter, possibly an amino acid:organic amine antiporter.

Bacteria
Proteobacteria
YjeM of E. coli
*2.A.3.7.6









Aspartate/Glutamate transporter of 488 aas and 12 TMSs, AcaP (Trip et al. 2013).

Bacteria
Firmicutes
AcaP of Lactococcus lactis
*2.A.3.7.7









Putriscine/agmatine transporter of 466 aas and 12 TMSs, AguD or YrfD (Trip et al. 2013).

Bacteria
Firmicutes
AguD of Lactococcus lactis
2.A.3.8:  The L-type Amino Acid Transporter (LAT) Family (Many LAT family members function as heterooligomers with rBAT and/or 4F2hc (TC #8.A.9))
*2.A.3.8.1









L-type neutral amino acid transporter, LAT1 (Na+-independent) (prefers amino acids with branched or aromatic side chains: Phe, Ile, Leu, Val, Trp, His; catalyzes obligatory exchange with μM affinities on the outside and mM affinities on the inside [1000x difference]). Both LAT1 and LAT2 (2.A.3.8.6) catalyze uptake of S-nitroso-L-cysteine. These and other LAT family members are specifically inhibited by 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid (Li and Whorton, 2005). Mediates tryptophan:kynurenine exchange (Kaper et al., 2007). Also transports thyroid hormones (Kinne et al., 2011).  The chicken orthologue transports thyrold hormones, especially T2, with low affinity (Nele Bourgeois et al. 2016). Transports certain thyroid hormones and their derivatives (Krause and Hinz 2017).

Eukaryota
Metazoa
LAT1 of Rattus norvegicus (Q63016)
*2.A.3.8.2









L-type neutral amino acid transporter, ASUR4 (Na+-independent)
Eukaryota
Metazoa
ASUR4 of Xenopus laevis (O13020)
*2.A.3.8.3









The schistosome neutral and cationic amino acid transporter, SPRM1lc (Na+-independent), (takes up phe, arg, lys, ala, gln, his, trp and leu; functions with SPRM1hc (TC# 8.A.9.3.1) (Krautz-Peterson et al., 2007)
Eukaryota
Metazoa
SPRM1lc of Schistosoma mansoni (Q26594)
*2.A.3.8.4









L-methionine transporter, MUP1.  Also transports selenomethionine (SeMet) (Kitajima et al. 2010).

Eukaryota
Fungi
MUP1 of Saccharomyces cerevisiae (P50276)
*2.A.3.8.5









Cystine/glutamate antiporter, xCT (requires the 4F2hc protein (TC #8.A.9.2.1)). Functions in the generation of glutathione and plays a role in the oxidative stress response (Wang et al. 2015).

Eukaryota
Metazoa
xCT of Mus musculus (Q9WTR6)
*2.A.3.8.6









L-type neutral amino acid transporter, LAT2 (Na+-independent with broad specificity for all L-isomers of neutral amino acids; preferred substrate: Phe, His, Trp, Ile, Val, Leu, Gln, Cys, Ser; catalyzes obligatory exchange with μM affinities on the outside and mM affinities on the inside [1000x difference]). Both LAT2 and LAT1 (2.A.3.8.1) catalyze uptake of S-nitro-L-cysteine (Li and Whorton, 2005). Also transports thyroid hormones (Kinne et al., 2011).

Eukaryota
Metazoa
LAT2 of Rattus norvegicus (Q9WVR6)
*2.A.3.8.7









y+LAT1 (transports neutral amino acids (i.e., Leu) in symport with Na+, Li+ or H+ in 1:1 stoichiometry; transports basic amino acids (i.e., Lys) by facilitated diffusion without a symported cation). Also transports the neurotoxicant, methylmercury-L-cysteine by molecular mimicry. Causes the Lysinuric protein intolerance condition in humans (Q9UM01) (Broer, 2008).
Eukaryota
Metazoa
y+LAT1 of Rattus norvegicus (Q9QZ66)
*2.A.3.8.8









Aspartate/glutamate Na+-independent transporter, AGT1
Eukaryota
Metazoa
AGT1 of Mus musculus (Q91WN3)
*2.A.3.8.9









Heteromeric amino acid transporter #1 (transports most neutral aas with highest rates for Ala and Ser (Km≈100 μM)). They function by obligatory aa:aa exchange (Veljkovic et al., 2004b).

Eukaryota
Metazoa
AAT1 of Caenorhabditis elegans (Q19834)
*2.A.3.8.10









Aromatic amino acid exchanger, AAT-9 (Veljkovic et al., 2004b)

Eukaryota
Metazoa
AAT-9 of Caenorhabditis elegans (Q9NA91)
*2.A.3.8.11









The aromatic-preferring amino acid transporter (ArpAT). Functions with rBAT or 4F2hc (8.A.9) and transports preferentially tyr and 3,4-dihydroxyphenylalanine (L-DOPA), but also ala, glu, ser, cys and arg by a Na+-independent mechanism (present in mouse, rat, dog and chicken, but silenced in humans and chimps)(Fernández et al., 2005; Sato et al., 2005)

Eukaryota
Metazoa
ArpAT of Mus musculus (Q50E62)
*2.A.3.8.12









The Ser/Thr exchange transporter (SteT) (also transports aromatic amino acids with lower efficiency) (Reig et al., 2007). The substrate-bound state of SteT shows increased conformational flexibility and kinetic stability, enabling transport of substrate across the cell membrane (Bippes et al. 2009). TMS8 sculpts the substrate-binding site and undergoes conformational changes during the transport cycle of SteT (Bartoccioni et al., 2010). Mutations allow substrate binding but not translocation. Other mutations stabilize the protein and result in higher production levels (Rodríguez-Banqueri et al. 2016).

Bacteria
Firmicutes
SteT of Bacillus subtilis (O34739)
*2.A.3.8.13









The Asc-type small neutral D- and L-amino acid:H+ symport transporter-1, Asc-1 (Slc7a10). Also transports amino acid related compounds. Heterodimeric; associates with 4F2hc (TC# 8.A.9.2.1) Most highly expressed in brain and lung, but to a lesser degree in placenta and small intestine. (Fukasawa et al., 2000)
Eukaryota
Metazoa
Asc-1 of Mus musculus (P63115)
*2.A.3.8.14









The Asc-type small neutral L-amino acid:H+ symport transporter-2 (Asc-2). Does not associate with 4F2hc or rBAT, but probably associates with some comparable heavy chain. Doesn't transport some substrates of Asc-1 such as α-aminoisobutyric acid and β-alanine (Chairoungdua et al., 2001)
Eukaryota
Metazoa
Asc-2 of Mus musculus (Q8VIE6)
*2.A.3.8.15









The b0,+ amino acid (cystine) transporter associated with the cystinuria-related type II membrane glycoprotein, BAT1 which forms a heterodimer with rBAT (TC# 8.A.9.1.1). Present in the apical membrane of renal proximal tubules (Chairoungdua et al., 1999)
Eukaryota
Metazoa
BAT1 of Rattus norvegicus (P82252)
*2.A.3.8.16









Low-affinity methionine permease, MUP3

Eukaryota
Fungi
MUP3 of Saccharomyces cerevisiae
*2.A.3.8.17









Putative fructoselysine transporter FrlA (Wiame and Van Schaftingen 2004). Also transports psicoselysine. 
Bacteria
Proteobacteria
FrlA of Escherichia coli
*2.A.3.8.18









Cystine/glutamate antiporter (Amino acid transport system xc-) (Calcium channel blocker resistance protein CCBR1) (Solute carrier family 7 member 11) (xCT).  The pathology and development of non-competive diaryl-isoxazole inhibitors have been presented (Newell et al. 2013).  In Lama paco (alpaca), the Slc7a11 porter of 503 aas and 12 TMSs probably functions in melanogenesis and coat color regulation (Tian et al. 2015).  Interacts with mucin-1 (MUC1-C; P15941) which forms a complex with xCT.  Together they maintain glutathione levels and redox balance and influence cancer development (Hasegawa et al. 2016).

Eukaryota
Metazoa
SLC7A11 of Homo sapiens
*2.A.3.8.19









B(0,+)-type amino acid transporter 1 (B(0,+)AT) (Glycoprotein-associated amino acid transporter b0,+AT1) (Solute carrier family 7 member 9)
Eukaryota
Metazoa
SLC7A9 of Homo sapiens
*2.A.3.8.20









Large neutral amino acids transporter small subunit 2 (L-type amino acid transporter 2) (hLAT2) (Solute carrier family 7 member 8). Certain detergents stabilize and allow purification of the 4F2hc-LAT2 complex, allowing the measurement of substrate binding. In addition, an improved 3D map could be obtained (Meury et al. 2014).  Transports many amino acids including thyroid hormones 3',3-T2 and T3 (Hinz et al. 2015; Kinne et al. 2015).

Eukaryota
Metazoa
SLC7A8 of Homo sapiens
*2.A.3.8.21









Asc-type amino acid transporter 1 (Asc-1) (Solute carrier family 7 member 10)
Eukaryota
Metazoa
SLC7A10 of Homo sapiens
*2.A.3.8.22









Y+L amino acid transporter 1 (Monocyte amino acid permease 2) (MOP-2) (Solute carrier family 7 member 7) (y(+)L-type amino acid transporter 1) (Y+LAT1) (y+LAT-1)
Eukaryota
Metazoa
SLC7A7 of Homo sapiens
*2.A.3.8.23









Y+L amino acid transporter 2 (Cationic amino acid transporter, y+ system) (Solute carrier family 7 member 6) (y(+)L-type amino acid transporter 2) (Y+LAT2) (y+LAT-2).  Transports certain thyroid hormones and their derivatives as well as multiple amino acids(Krause and Hinz 2017).

Eukaryota
Metazoa
SLC7A6 of Homo sapiens
*2.A.3.8.24









Solute carrier family 7 member 13 (Sodium-independent aspartate/glutamate transporter 1) (X-amino acid transporter 2)
Eukaryota
Metazoa
SLC7A13 of Homo sapiens
*2.A.3.8.25









Large neutral amino acids transporter small subunit 1 (4F2 light chain) (4F2 LC) (4F2LC) (CD98 light chain) (Integral membrane protein E16) (L-type amino acid transporter 1) (hLAT1) (Solute carrier family 7 member 5) (y+ system cationic amino acid transporter).  The heavy chain, CD98hc, modulates integrin signaling, plays a role in cell-to-cell fusion, and is essential for Brucella infection (Keriel et al. 2015).  In addition to L-amino acids, Lat1 in conjunction with 4F2hc, transports S-nitroso-L-cysteine (Li and Whorton 2007).

Eukaryota
Metazoa
SLC7A5 of Homo sapiens
*2.A.3.8.26









Unchracterized transporter

Bacteria
Actinobacteria
Uncharacterized permease of Streptomyces coelicolor
*2.A.3.8.27









Amino acid transporter 6 (AAT-6). Interacts with NRFL-1, the C. elegans NHERF orthologue to promote localization to the intestinal luminal membrane (Hagiwara et al. 2012).

Eukaryota
Metazoa
AAT-6 of Caenorhabditis elegans
*2.A.3.8.28









Serine/threonine exchanger, SteT

Bacteria
Bacteroidetes/Chlorobi group
SteT of Cecembia lonarensis
*2.A.3.8.29









Cationic amino acid transporter, y+LAT1.  95% identical to a characterized carp orthologue (Yang et al. 2013).

Eukaryota
Metazoa
y+LAT1 cationic amino acid transporter of Danio rerio (Zebra fish)
*2.A.3.8.30









Putative amino acid porter of 512 aas and 14 TMSs.

Archaea
Crenarchaeota
Amino acid porter of Sulfolobus islandica
*2.A.3.8.31









Putative polyamine transporter of 537 aas and 12 TMSs

Bacteria
Tenericutes
Putative polyamine porter of Mycoplasma (Acholeplasma) florum
*2.A.3.8.32









Large neutral amino acid transporter, CD98lc (LAT), of 442 aas.  Functions with CD98hc (TC# 8.A.9.2.3) (Reynolds et al. 2009).  CD98hc also modulates integrin signaling (Prager et al. 2007), plays a role in cell-to-cell fusion, and is essential for Brucella infection (Keriel et al. 2015Keriel et al. 2015).

Eukaryota
Metazoa
CD98lc of Drosophila melanogaster
2.A.3.9:  The Spore Germination Protein (SGP) Family
*2.A.3.9.1









Spore germination protein A2 (AB) (amino acid [L-alanine] receptor.) GerAA, GerAB and GerAC form a receptor complex in the spore inner membrane. GerAC is a lipoprotein (Cooper and Moir, 2011).

Bacteria
Firmicutes
GerAB of Bacillus subtilis (P07869)
*2.A.3.9.2









Spore germination protein B2 (BB) (amino acid [D-alanine and L-asparagine] receptor)
Bacteria
Firmicutes
GerBB of Bacillus subtilis
*2.A.3.9.3









Spore germination protein K2 (KB) (probable amino acid receptor)
Bacteria
Firmicutes
GerKB of Bacillus subtilis
*2.A.3.9.4









Spore germination protein YndE
Bacteria
Firmicutes
YndE of Bacillus subtilis
*2.A.3.9.5









Spore germination protein of 368 aas and 10 TMSs.  Maps adjacent to a putative ABC transporter of unknown specificity (F8FLY8, F8FLY7, F8FLY5). 

Bacteria
Firmicutes
SGP of Paenibacillus mucilaginosus
2.A.3.10:  The Yeast Amino Acid Transporter (YAT) Family
*2.A.3.10.1









High affinity histidine permease (also implicated in Mn2+ efflux; Co2+, Ni2+, Zn2+ and Cu2+ uptake)
Eukaryota
Fungi
Hip1 of Saccharomyces cerevisiae (P06775)
*2.A.3.10.2









General amino acid permease (all L-amino acids and some D-amino acids as well as β-alanine, polyamines and GABA). Systematic mutational analysis of the intracellular regions of yeast Gap1 permease revealed multiple intracellular regions involved in its secretion, transport activity, and down-regulation (Igarashi and Kashiwagi 2010; Merhi et al., 2011). GAP1 is a "transceptor", fuctioning in both transport and reception, necessary for cAMP-independent activation of the Protein Kinase A pathway under conditions of re-addition of amino acids to cells previously starved for amino acids (Diallinas 2017).

Eukaryota
Fungi
Gap1 of Saccharomyces cerevisiae (P19145)
*2.A.3.10.3









Proline permease
Eukaryota
Fungi
Put4 of Saccharomyces cerevisiae (P15380)
*2.A.3.10.4









Arginine permease
Eukaryota
Fungi
Can1 of Saccharomyces cerevisiae (P04817)
*2.A.3.10.5









High affinity glutamine permease
Eukaryota
Fungi
Gnp1 of Saccharomyces cerevisiae (P48813)
*2.A.3.10.6









Leu/Val/Ile amino acid permease
Eukaryota
Fungi
Bap2 of Saccharomyces cerevisiae (P38084)
*2.A.3.10.7









Asn/Gln permease
Eukaryota
Fungi
Agp1 of Saccharomyces cerevisiae (P25376)
*2.A.3.10.8









Tryptophan permease, Tat2. Regulated via endocytosis by ATP-binding Cassette Transporters, Pdr5 (3.A.1.205.1) and Yor1 (3.A.208.3) as well as a seven-transmembrane protein, RSB1 (9.A.27.1.2) (Johnson et al., 2010).  Residues involved in binding and catalysis have been identified (Kanda and Abe 2013).  residues and regions important for proper folding and ER retention have been identified (Mochizuki et al. 2015).

Eukaryota
Fungi
Tat2 of Saccharomyces cerevisiae (P38967)
*2.A.3.10.9









Val/Tyr/Trp permease
Eukaryota
Fungi
Val1 (Tat1) of Saccharomyces cerevisiae (P38085)
*2.A.3.10.10









Lysine permease
Eukaryota
Fungi
Lyp1 of Saccharomyces cerevisiae (P32487)
*2.A.3.10.11









Basic amino acid permease
Eukaryota
Fungi
Alp1 of Saccharomyces cerevisiae (P38971)
*2.A.3.10.12









Leucine sensor/transcription factor. Mutants hyper- and hyposensitive to inducer (Poulsen et al., 2008) suggest a sensor mechanism involving outward and inward facing conformations.
Eukaryota
Fungi
Ssy1 of Saccharomyces cerevisiae (Q03770)
*2.A.3.10.13









Dicarboxylic amino acid permease
Eukaryota
Fungi
Dip5 of Saccharomyces cerevisiae (P53388)
*2.A.3.10.14









General amino acid permease with broad specificity, Agp3
Eukaryota
Fungi
Agp3 of Saccharomyces cerevisiae (P43548)
*2.A.3.10.15









S-adenosylmethionine uptake permease, SAM3 (also takes up polyamines, glutamate, lysine and the toxic S-adenosylmethionine analogue sinefungin) (Uemura et al., 2007; Zheng et al., 2007; Kashiwagi and Igarashi 2011).

Eukaryota
Fungi
SAM3 or Agp3 (YPL274w) of Saccharomyces cerevisiae (Q08986)
*2.A.3.10.16









S-methylmethionine uptake permease, Mmp1
Eukaryota
Fungi
Mmp1 (YLL061w) of Saccharomyces cerevisiae (Q12372)
*2.A.3.10.17









General amino acid uptake permease, GAP1
Eukaryota
Fungi
GAP1 of Hebeloma cylindrosporum (Q8J266)
*2.A.3.10.18









The aromatic amino acid and leucine permease, ArlP (may be a general amino acid permease for neutral and basic [but not acidic] amino acids)
Eukaryota
Fungi
ArlP of Penicillium chrysogenum (Q8NKC4)
*2.A.3.10.19









The high affinity polyamine (spermidine > putrescine)/carnitine, low affinity amino acid transporter, AGP2 (Aouida et al., 2005; Uemura et al., 2007)

Eukaryota
Fungi
AGP2 of Saccharomyces cerevisiae (P38090)
*2.A.3.10.20









The high affinity basic amino acid (Arg, Lys, His) transporter, Can1 (Matijekova and Sychrova, 1997)
Eukaryota
Fungi
Can1 of Candida albicans (P43059)
*2.A.3.10.21









The basic amino acid (canavanine sensitivity) transporter, Cat1 (Aspuria and Tamanoi, 2008).
Eukaryota
Fungi
Cat1 of Schizosaccharomyces pombe (Q9URZ4)
*2.A.3.10.22









Arbuscular mycorrhizal fungal proline:H+ symporter, AAP1 (binds and probably transports nonpolar, hydrophobic amino acids) (Cappellazzo et al., 2008).
Eukaryota
Fungi
AAP1 of Glomus mosseae (Q2VQZ4)
*2.A.3.10.23









Amino acid permease, GAP1. Transports Arg, Met, Leu and Phe (Kraidlova et al., 2011).

Eukaryota
Fungi
GAP1 of Candida albicans (Q5AG77)
*2.A.3.10.24









General amino and permease and transceptor, GAP2. Transports all amino acids including citruline and eight tested toxic amino acid derivatives (Kraidlova et al., 2011).

Eukaryota
Fungi
GAP2 of Candida albicans (Q59YT0)
*2.A.3.10.25









Arginine transporter, GAP4 (Kraidlova et al., 2011)

Eukaryota
Fungi
GAP4 of Candida albicans (Q59W33)
*2.A.3.10.26









General amino acid porter, GAP6. Transports almost all amino acids tested except arginine and citruline (Kraidlova et al., 2011).

Eukaryota
Fungi
GAP6 of Candida albicans (Q59NZ6)
*2.A.3.10.27









Valine amino-acid permease (Branched-chain amino-acid permease 3)
Eukaryota
Fungi
BAP3 of Saccharomyces cerevisiae
*2.A.3.10.28









Probable amino-acid permease Meu22 (Meiotic expression up-regulated protein 22)

Eukaryota
Fungi
Meu22 of Schizosaccharomyces pombe
2.A.3.11:  The Aspartate/Glutamate Transporter (AGT) Family
*2.A.3.11.1









The aspartate uptake permease, YveA (also transports L-aspartate hydroxamate and glutamate, and possibly asparagine and glutamine; Lorca et al., 2003)
Bacteria
Firmicutes
YveA of Bacillus subtilis
2.A.3.12:  The Polyamine:H+ Symporter (PHS) Family
*2.A.3.12.1









The plasma membrane polyamine (putrescine, spermidine):H+ uptake symporter, LmPOT1 (inhibited by pentamidine and protonophores) (Hasne and Ullmann, 2005)
Eukaryota
Kinetoplastida
POT1 of Leishmania major (AAW52506)
*2.A.3.12.2









The putriscene-cadaverine polyamine uptake porter, POT1.1 (613aas; 12-13 TMSs) Also called PAT12; transports paraquot as well as polyamines (Soysa et al. 2013; Fujita and Shinozaki 2014)

Eukaryota
Kinetoplastida
POT1.1 of Trypansosoma cruzi
*2.A.3.12.3









Plasma membrane polyamine/paraquot uptake transporter of 490 aas, RMV1. Also called PUT3 and LAT1. Mutations give rise to partial paraquot (a toxic common herbicide that generates superoxide and reactive oxygen species (ROS)) (Fujita and Shinozaki 2014).

Eukaryota
Viridiplantae
RMV1 of Arabidopsis thaliana
*2.A.3.12.4









Golgi polyamine/paraquot uptake transporter of 478 aas, LAT4. Also called PUT2 and PAR1.  Mutations give rise to paraquot resistance (Par1) both in A. thaliana and in rice.  Probably present in the chloroplast membrane (Fujita and Shinozaki 2014).

Eukaryota
Viridiplantae
LAT4 of Arabidopsis thaliana
*2.A.3.12.5









Spermidine-preferring polyamine transporter, PUT1 of 531 aas.  Also transports paraquot (Fujita and Shinozaki 2014).

Eukaryota
Viridiplantae
PUT1 of Oryza sativa
2.A.3.13:  The Amino Acid Efflux (AAE) Family
*2.A.3.13.1









The hydrophobic amino acid efflux transporter, YjeH (exports L-methionine and other neutral, hydrophobic amino acids such as Leu, Ile and Val; R. Figge, personal communication; Liu et al. 2015).

Bacteria
Proteobacteria
YjeH of E. coli (P39277)
*2.A.3.13.2









The Ceftriaxone resistance porter, YjeH (Hu et al. 2007).

Bacteria
Proteobacteria
YjeH of Salmonella enterica (serovar Typhimurium) (Q8ZKC0)
2.A.3.14:  The Unknown APC-1 (U-APC1) Family
*2.A.3.14.1









APC family member; Ala/Val/Leu-rich protein encoded within an operon that also encodes a 23S rRNA methyl transferase, RumA. Two half sized TrkA proteins are encoded within an operon that is divergently transcribed. Possibly, they regulate transport.

Bacteria
Actinobacteria
AVL-rich protein of Salinispora tropica (A4X503)
*2.A.3.14.2









Uncharacterized transporter

Bacteria
Actinobacteria
Uncharacterized porter of Streptomyces coelicolor
*2.A.3.14.3









APC protein with 610 aas and 12 TMSs.  77% identical to an orthologue in Weissella viridescens that serves as a receptor or uptake transporter for the two peptide bacteriocin, plantaricin JK (1.C.30.1.1) (Oppegård et al. 2016; Ekblad et al. 2017).

Bacteria
Proteobacteria
APC uptake porter of Weissella confusa
2.A.3.15:  The Unknown APC-2 (U-APC2) Family
*2.A.3.15.1









Hypothetical transporter  (H.T.) (442 aas; 13 TMSs)

Archaea
Euryarchaeota
H.T. of Picrophilus torridus (Q6L0Y3) 
*2.A.3.15.2









Cationic amino acid transporter, CAAT (462 aas; 12 TMSs) 

Archaea
Euryarchaeota
CAAT of Thermoplasma acidophilum (Q9HJ13)
*2.A.3.15.3









Amino acid permease (AAP) (417 aas; 12 TMSs) 

Archaea
Crenarchaeota
AAP of Sulfolobus solfataricus (Q97YX9)
*2.A.3.15.4









Hypothetical protein (H.P.) 

Eukaryota
Dictyosteliida
H.P. of Dictyostelium discoideum (Q54KK4)
*2.A.3.15.5









Uncharacterized transporter

Bacteria
Actinobacteria
Uncharacterized porter of Streptomyces coelicolor