TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameDomainKingdom/PhylumProtein(s)
*2.A.18.1.1









Auxin:H+ symporter (auxin influx), AUX or LAX (Reinhardt et al., 2003; Carraro et al., 2012).  In the PILS (Pin-like) family; members are located in the endoplasmic reticular membrane (Balzan et al. 2014).  Expression patterns of PILS family members have been studied (Mohanta et al. 2015).

Eukaryota
Viridiplantae
Aux-1 of Arabidopsis thaliana
*2.A.18.2.1









General amino acid permease 1, AAP1 (transports most neutral and acidic amino acids but not aspartate or the basic amino acids)
Eukaryota
Viridiplantae
AAP1 of Arabidopsis thaliana
*2.A.18.2.2









Lysine/histidine transporter, LHT1
Eukaryota
Viridiplantae
LHT1 of Arabidopsis thaliana
*2.A.18.2.3









General amino acid transporter 3, AAP3 (transports all neutral, acidic and basic amino acids tested)
Eukaryota
Viridiplantae
AAP3 of Arabidopsis thaliana
*2.A.18.2.4









General amino acid transporter 6, AAP6 (transports all neutral and acidic amino acids tested including aspartate, and basic amino acids are transported with low affinity) (Okumoto et al., 2002)
Eukaryota
Viridiplantae
AAP6 of Arabidopsis thaliana
*2.A.18.2.5









General amino acid transporter 8, AAP8 (transports all amino acids, but the basic amino acids are transported
with low affinity (Okumoto et al., 2002))
Eukaryota
Viridiplantae
AAP8 of Arabidopsis thaliana
*2.A.18.2.6









Lysine-Histidine Transporter-7 (LHT7) found in mature pollen (Bock et al., 2006) (most like 2.A.18.2.2; 30% identity)

Eukaryota
Viridiplantae
LHT7 of Arabidopsis thaliana (Q84WE9)
*2.A.18.2.7









Amino acid permease 2 (Amino acid transporter AAP2)
Eukaryota
Viridiplantae
AAP2 of Arabidopsis thaliana
*2.A.18.2.8









Lysine histidine transporter-like 8 (Amino acid transporter-like protein 1)
Eukaryota
Viridiplantae
AATL1 of Arabidopsis thaliana
*2.A.18.2.9









Lysine/histidine transporter 2 (AtLHT2) (Amino acid transporter-like protein 2)

Eukaryota
Viridiplantae
LHT2 of Arabidopsis thaliana
*2.A.18.2.10









Probable amino acid permease 7 (Amino acid transporter AAP7)
Eukaryota
Viridiplantae
AAP7 of Arabidopsis thaliana
*2.A.18.3.1









Proline permease 1
Eukaryota
Viridiplantae
Prt1 of Arabidopsis thaliana
*2.A.18.3.2









Proline/GABA/glycine betaine permease, ProT1
Eukaryota
Viridiplantae
ProT1 of Lycopersicon esculentum
*2.A.18.4.1









Neutral amino acid permease
Eukaryota
Fungi
AAP1 of Neurospora crassa
*2.A.18.4.2









Aromatic and neutral amino acid permease, PcMtr (Trip et al., 2004)
Eukaryota
Fungi
PcMtr of Penicillium chrysogenum (AAT45727)
*2.A.18.5.1









Vesicular γ-aminobutyric acid (GABA) and glycine transporter (Aubrey et al., 2007)

Eukaryota
Metazoa
UNC-47 of Caenorhabditis elegans
*2.A.18.5.2









The vacuolar amino acid transporter AVT1 (catalyzes uptake into yeast vacuoles of large neutral amino acids including tyr, gln, asn, leu and ile)
Eukaryota
Fungi
AVT1 of Saccharomyces cerevisiae
*2.A.18.5.3









The vacuolar GABA and glycine uptake transporter, VGAT. Also called "vesicular inhibitory amino acid transporter" (VIAAT); it is a 2Cl-/γ-aminobutyrate or glycine co-transporter in synaptic vesicles (Juge et al., 2009). GlyT2 and VIAAT cooperate to determine the vesicular glycinergic phenotype (Aubrey et al., 2007).

Eukaryota
Metazoa
VGAT of Mus musculus (O35633)
*2.A.18.5.4









Vesicular inhibitory amino acid transporter (GABA and glycine transporter; Solute carrier family 32 member 1; Vesicular GABA transporter; VGAT; hVIAAT).  Probably functions by GABA:H+ antiport (Farsi et al. 2016).

Eukaryota
Metazoa
SLC32A1 of Homo sapiens
*2.A.18.5.5









The aggression-related transporter, CG13646 of 527 aas and 11 TMSs. Reduction in expression of CG13646 by approximately half leads to a hyperaggressive phenotype partially resembling that seen in Bully flies (Chowdhury et al. 2017). Members of this family are involved in glutamine/glutamate and GABA cycles of metabolism in excitatory and inhibitory nerve terminals.

Eukaryota
Metazoa
CG13646 of Drosophila melanogaster
*2.A.18.6.1









Neuronal glutamine (System A-like) transporter, GlnT
Eukaryota
Metazoa
GlnT of Rattus norvegicus (Q9JM15)
*2.A.18.6.2









Liver histidine and glutamine specific system N-like, Na+-dependent amino acid transporter, mNAT. Also called SNAT3. SNAT3 trafficking occurs in a dynamin-independent manner and is influenced by caveolin (Balkrishna et al., 2010).

Eukaryota
Metazoa
mNAT of Mus musculus (Q9JLL8)
*2.A.18.6.3









System N1, SNAT3 [glutamine/histidine/asparagine/alanine]:[Na+ + H+] sym/antiporter (1 aa + 2 Na+ cotransported against 1 H+ antiported out) (probable orthologue of mNAT). Li+ can substitute for Na+; system N1 can function bidirectionally. SNAT3 is a primarily a glutamine transporter required for amino acid homeostasis. Loss cannot be compensated, suggesting that this transporter is a major route of glutamine transport in the liver, brain, and kidney (Chan et al. 2015).

Eukaryota
Metazoa
SLC38A3 of Homo sapiens
*2.A.18.6.4









Plasma membrane System A-like neutral amino acid transporter, SA1, SAT2 or SNAT2 (transports small, neutral aliphatic amino acids including α-(methylamino)isobutyrate, mAIB with Na+ (1:1 stoichiometry; Km = 200-500 μM)). Asparagine 82 controls the interaction of Na+ with the transporter (Zhang and Grewer, 2007). The C-terminal domain regulates transport activity through a voltage-dependent process (Zhang et al., 2011).

Eukaryota
Metazoa
SAT2 of Rattus norvegicus (Q9JHE5)
*2.A.18.6.5









Na+-dependent system A-like transporter, System A2 or ATA2 (transports neutral amino acids with decreasing affinity in the order: MeAIB, Ala, Gly, Ser, Pro, Met, Asn, Gln, Thr, Leu and Phe). The neuronal system A2 has been reported to transport Asn and Gln with higher affinity than for other neutral amino acids. [ATA2 is stored in the Golgi network and released by insulin stimulus in adipocytes (Hatanaka et al., 2006a).] Its levels are regulated by ubiquitin ligase, Nedd4-2, which causes endocytotic sequestration and proteosomal degradation (Hatanaka et al., 2006b). SNAT2 also functions as a mammalian amino acid transceptor (transporter/receptor), acting in an autoregulatory gene expression pathway (Hyde et al., 2007). It also mediates an anion leak conductance that is differentially inhibited by transported substrates (Zhang and Grewer, 2007). Also transports homocysteine (Tsitsiou et al., 2009).
Eukaryota
Metazoa
SLC38A2 of Homo sapiens
*2.A.18.6.6









The vacuolar amino acid transporter, AVT6 (catalyzes efflux from yeast vacuoles of acidic amino acids, Asp and Glu)
Eukaryota
Fungi
AVT6 of Saccharomyces cerevisiae (P40074)
*2.A.18.6.7









The Na-dependent alanine/α-(methylamino) isobutyric acid-transporting system A, ATA3 or SNAT4. Transports most neutral short chain amino acids electrogenically. Present only in liver and skeletal muscle. 47% and 57% identical to ATA1 and ATA2, respectively. A 10TMS topology [with N-and C-termini outside and a large N-glycosylated, extracellular loop domain (residues 242-335)] has been established (Shi et al., 2011). (Km(ALA)= 4mM; Na+:Ala= 1:1) (Sugawara et al., 2000)

Eukaryota
Metazoa
ATA3 of Rattus norvegicus (Q9EQ25)
*2.A.18.6.8









Second subtype of system N; glutamine transporter, SN2. Prevalent in liver, but detectable in other tissues. Amino acid uptake is coupled to Na+ influx and H+ efflux (Nakanishi et al., 2001)

Eukaryota
Metazoa
SN2 of Rattus norvegicus (Q91XR7)
*2.A.18.6.9









Arginine-specific transporter, AAP3 (KM (Arg) = 2μM)
Eukaryota
Kinetoplastida
AAP3 of Leishmania donovani (Q86G79)
*2.A.18.6.10









Vacuolar broad specificity amino acid transporter 5 Avt5. Transports histidine, gluatmate, tyrosine, arginine, lysine and serine (Chardwiriyapreecha et al., 2010).

Eukaryota
Fungi
Avt5 of Saccharomyces cerevisiae (P38176)
*2.A.18.6.11









SLC38 member 6, SNAT6. Na+-dependent synaptic vesicle amino acid release porter (Gasnier, 2004) (transports amino acids, glutamine, glycine and γ-amino butyric acid (GABA)).  It seems to be the only glutamine transporter in the brain, being present in excitatory neurons, particularly at the synapses (Bagchi et al. 2014).

Eukaryota
Metazoa
SLC38A6 of Homo sapiens
*2.A.18.6.12









Solute carrier family 38, member 8, SLC38A8, expressed only in the eye.  This protein is probably a Na+/H+-dependent amino acid transporter which when defective, gives rise to foveal hypoplasia associated with congenital nystagmus and reduced visual acuity (Perez et al. 2014).

Eukaryota
Metazoa
SLC38A8 of Homo sapiens
*2.A.18.6.13









Sodium-coupled neutral amino acid transporter 7, SNAT7.  Transports L-glutamine in excitatory neurons 9but not astrocytes) as the preferred substrate, particularly at synapses, but also transports L-glutamate and other amino acids with polar side chains such as L-histidine and L-alanine (Hägglund et al. 2011).

Eukaryota
Metazoa
SLC38A7 of Homo sapiens
*2.A.18.6.14









Sodium-coupled neutral amino acid transporter 1 (Amino acid transporter A1; SLC38A1; SNAT1; N-system amino acid transporter 2; Solute carrier family 38 member 1; System A amino acid transporter 1; System N amino acid transporter 1).  When overexpressed, it causes Rett syndrome (RTT), an autism spectrum disorder caused by loss-of-function mutations in the gene encoding MeCP2, an epigenetic modulator (transcriptional repressor) of SLC38A1, which encodes a major glutamine transporter (SNAT1).  Because glutamine is mainly metabolized in the mitochondria where it is used as an energy substrate and a precursor for glutamate production, SNAT1 overexpression in MeCP2-deficient microglia impairs glutamine homeostasis, resulting in mitochondrial dysfunction as well as microglial neurotoxicity because of glutamate overproduction (Perez et al. 2014).

Eukaryota
Metazoa
SLC38A1 of Homo sapiens
*2.A.18.6.15









Neutral amino acid transporter 5 (Solute carrier family 38 member 5, SNAT5) (System N transporter 2, SN2).  Transports glutamine, histidine and glycine as well as other amino acids.  Present in glial cells where it probably functions in neurotransmitter clearance from synapses (Rodríguez et al. 2014).

Eukaryota
Metazoa
SLC38A5 of Homo sapiens
*2.A.18.6.16









Sodium-coupled amino acid transporter 10, SNAT10.  Expressed in several endocrine organs (Sundberg et al. 2008). Transports glutamine, glutamate and aspartate in neuronal and astrocytic cells (Hellsten et al. 2017).

Eukaryota
Metazoa
SLC38A10 of Homo sapiens
*2.A.18.6.17









Sodium-coupled neutral amino acid transporter 4 (Amino acid transporter A3) (Na(+)-coupled neutral amino acid transporter 4) (Solute carrier family 38 member 4) (System A amino acid transporter 3) (System N amino acid transporter 3)
Eukaryota
Metazoa
SLC38A4 of Homo sapiens
*2.A.18.6.18









Putative sodium-coupled neutral amino acid transporter 11, SNAT11 (Forde et al. 2014).

Eukaryota
Metazoa
SLC38A11 of Homo sapiens
*2.A.18.6.19









Vacuolar amino acid transporter 7
Eukaryota
Fungi
AVT7 of Saccharomyces cerevisiae
*2.A.18.6.20









Vacuolar amino acid transporter 2
Eukaryota
Fungi
AVT2 of Saccharomyces cerevisiae
*2.A.18.7.1









The vacuolar amino acid transporter, AVT3 (catalyzes efflux from yeast vacuoles of large neutral amino acids such as tyr, gln, asn, leu and ile)
Eukaryota
Fungi
AVT3 of Saccharomyces cerevisiae
*2.A.18.7.2









Vacuolar amino acid transporter 4
Eukaryota
Fungi
AVT4 of Saccharomyces cerevisiae
*2.A.18.7.3









Vacuolar amino acid transporter 3, Avt3.  Catalyzes efflux from vacuoles of large hydrophobic and hydrophilic neutral amino acids, and is required for sporulation.

Eukaryota
Fungi
Avt3 of Schizosaccharomyces pombe
*2.A.18.7.4









Proline/alanine transporter of 488 aas and 10 TMSs, AAP24. The first 18 amino acids of the negatively charged N-terminal LdAAP24 tail are required for alanine transport and may facilitate the electrostatic interactions of the entire negatively charged N-terminal tail with the positively charged internal loops in the transmembrane domain.  This mechanism may underlie regulation of substrate flux rate for this and other transporters (Schlisselberg et al. 2015).

Eukaryota
Kinetoplastida
AAP24 of Leishmania infantum
*2.A.18.8.1









The electrogenic, proton-dependent amino acid:H+ symporter, PAT1 (Slc36A1) (catalyzes uptake of L-Gly, L-Ala, L-Pro, γ-amino butyrate, and short chain D-amino acids) (proline, hydroxyproline: H+ = 1:1) (found in lysosomes) In humans, this is the iminoglycinuria protein (Boll et al., 2004Miyauchi et al., 2005; Broer, 2008). A disulfide bridge is essential for transport function (Dorn et al., 2009). Transports taurine and β-alanine by H+ symport with low affinity and high capacity across the intestinal brush boarder membrane (Anderson et al., 2009). Exhibits low affinity (Km= 1-10 mM) and transports amino acid-based drugs used to treat epilepsy, schizophrenia, bacterial infections, hyperglycemia and cancer (Thwaites and Anderson, 2011).

Eukaryota
Metazoa
mPAT1 of Mus musculus (Q8K4D3)
*2.A.18.8.2









Electrogenic, proton-coupled, amino acid symporter 2 (PAT2; Tramdorin-1; SLC36A2) (transports small amino acids: glycine, alanine and proline; found in the ER, not in lysosomes, of neuronal cells in the brain and spinal cord; it can catalyze bidirectional transport depending on the driving force) (Boll et al., 2004Rubio-Aliaga et al., 2004). SLC36A2 is expressed at the apical surface of the human renal proximal tubule where it functions in the reabsorption of glycine, proline, hydroxyproline and amino acid derivatives with narrower substrate selectivity and higher affinity (Km 0.1-0.7 mM) than SLC36A1. Mutations in SLC36A2 lead to hyperglycinuria and iminoglycinuria.

Eukaryota
Metazoa
PAT2 of Mus musculus (AAH44800)
*2.A.18.8.3









Amino acid transporter (low capacity, high affinity) and amino acid-dependent signal transduction protein, Pathetic (Path) (Goberdhan et al., 2005)
Eukaryota
Metazoa
Path of Drosophila melanogaster (Q9VT04)
*2.A.18.8.4









H+-coupled amino acid transporter-3 (SLC36A3).  SLC36A3 is expressed only in testes and has no known function (Thwaites and Anderson 2011).

Eukaryota
Metazoa
SLC36A3 of Homo sapiens
*2.A.18.8.5









H+-coupled amino acid transporter-4; SLC36A4.  SLC36A4 is widely distributed  and has high-affinity (Km = 2-3 µM) for proline and tryptophan (Thwaites and Anderson 2011).

Eukaryota
Metazoa
SLC36A4 of Homo sapiens
*2.A.18.8.6









Proton-coupled amino acid transporter 2 (Proton/amino acid transporter 2) (Solute carrier family 36 member 2) (Tramdorin-1)
Eukaryota
Metazoa
SLC36A2 of Homo sapiens
*2.A.18.8.7









Proton-coupled amino acid transporter 1 (Proton/amino acid transporter 1) (hPAT1) (Solute carrier family 36 member 1).  SLC36A1 is expressed at the luminal surface of the small intestine but is also commonly found in lysosomes in many cell types (including neurones), suggesting that it is a multipurpose carrier with distinct roles in different cells including absorption in the small intestine and as an efflux pathway following intralysosomal protein breakdown. SLC36A1 has a relatively low affinity (K(m) 1-10 mM) for its substrates, which include zwitterionic amino and imino acids, heterocyclic amino acids and amino acid-based drugs and derivatives used experimentally and/or clinically to treat epilepsy, schizophrenia, bacterial infections, hyperglycaemia and cancer (Thwaites and Anderson 2011).  hPAT1 transports the pyridine alkaloids, arecaidine, guvacine and isoguvacine, across the apical membrane of enterocytes and might be responsible for the intestinal absorption of these drug candidates (Voigt et al. 2013).

Eukaryota
Metazoa
SLC36A1 of Homo sapiens
*2.A.18.8.8









Putative amino acid permease F59B2.2
Eukaryota
Metazoa
F59B2.2 of Caenorhabditis elegans
*2.A.18.9.1









Na+-coupled high affinity arginine transporter, SLC38A9 (561aas; 11 TMSs).  The rapamycin complex 1 (mTORC1) protein kinase is a master growth regulator that responds to multiple environmental cues. Amino acids stimulate, in a Rag-, Ragulator-, and vacuolar ATPase-dependent fashion, the translocation of mTORC1 to the lysosomal surface, where it interacts with its activator Rheb. Wang et al. 2015 showed that lysosomal SLC38A9 interacts with Rag GTPases and Ragulator in an amino acid-sensitive fashion. SLC38A9 transports arginine, and loss of SLC38A9 represses mTORC1 activation by amino acids, particularly arginine. Overexpression of SLC38A9 or just its Ragulator-binding domain makes mTORC1 signaling insensitive to amino acid starvation but not to Rag activity. Thus, SLC38A9 functions upstream of the Rag GTPases and is probably the arginine sensor for the mTORC1 pathway.  Jung et al. 2015 confirmed SLC38A9 to be a Rag-Ragulator complex member, transducing amino acid availability to mTORC1. Lysosomal cholesterol activates TORC1 via an SLC38A9-Niemann-Pick C1 signaling complex (Castellano et al. 2017).

Eukaryota
Metazoa
SLC38A9 of Homo sapiens
*2.A.18.10.1









Putative amino acid transporter, AAT

Eukaryota
Metazoa
AAT of Homo sapiens (Q8NE00)
*2.A.18.10.2









Putative amino acid transporter, AAT

Eukaryota
Entamoeba
AAT of Entamoeba histolytica (C4LSN3)
*2.A.18.10.3









Putative amino acid transporter, AAT

Eukaryota
Hexamitidae
AAT of Giardia intestinalis (C6LXJ3)
*2.A.18.10.4









AAAP homologue

Eukaryota
Intramacronucleata
AAAP homologue of Tetrahymena thermophilus