TCDB is operated by the Saier Lab Bioinformatics Group
TCIDNameOrganismal TypeExample
2.A.17.1.1









Di- or tripeptide:H+ symporter
Bacteria
DtpT of Lactococcus lactis (P0C2U2)
2.A.17.1.2









The di/tripeptide:H+ symport permease, TppB (DtpA or YdgR) (transports di and tripeptides and peptidomimetics such as aminocephalosporins (Weitz et al., 2007).  The transporter has two alternate conformations, one of which is promoted by inhbitor binding (Bippes et al. 2013).

Bacteria

TppB of E. coli (P77304)
2.A.17.1.3









The dipeptide/tripeptide:H+ symport permease, DtpB (YhiP) (transports glycyl-sarcosine (Gly-Sar) with low affinity (6mM) and the toxic dipeptide, alafosfalin (Harder et al., 2008)
Bacteria
DtpB of E. coli (P36837)
2.A.17.1.4









DtpD (YbgH) peptide transporter (a projection structure at 19 Å resolution is available; Casagrande et al., 2009).

Bacteria

DtpD of E. coli (P75742)
2.A.17.1.5









Peptide transporter, YjdL (preference for di-peptides) (Ernst et al., 2009; Gabrielsen et al., 2011; Jensen et al., 2011)

Bacteria

YjdL of E. coli (P39276)
2.A.17.1.6









POT famiy di- and tri-peptide porter, DtpT. 3-d structures (PDB:24APS) are available for an inward open conformation. A hinge-like movement in the C-terminal half facilitates opening of an intracellular gate controlling access to a central peptide binding site. Salt bridges may orchestrate alternating access (Solcan et al., 2012).

Bacteria

Peptide porter, DtpT of Streptococcus thermophilus (Q5M4H8)
2.A.17.1.7









Peptide uptake transporter of 496 aas, POT.  The 3-d structure has been determined to 1.9Å resolution leading to a proposed mechanism (Doki et al. 2013).  Glu310 first may bind the carboxyl group of the peptide substrate. Then deprotonation of Glu310 in the inward open state triggers the release of the bound peptide toward the intracellular space, and salt bridge formation between Glu310 and Arg43 induces the transition state to the occluded conformation.

Firmicutes

POT of Geobacillus kaustophilus
2.A.17.2.1









Peptide:H+ symporter
Plants
PTR2-A of Arabidopsis thaliana
2.A.17.2.2









Peptide:H+ symporter (dipeptides preferred; Cai et al., 2007).
Yeast
PTR2 of Saccharomyces cerevisiae
2.A.17.2.11









The Ca2+:H+ antiporter, YfkE; homotrimer with subunit size of 451 aas.  The 3-d x-ray strcuture is known to 3.1 Å resolution (Wu et al. 2013).  The conformational transition is triggered by the rotation of the kink angles of transmembrane helices 2 and 7 and is mediated by large conformational changes in their adjacent transmembrane helices 1 and 6.  The inward facing conformation contrasts with the outward facing conformation demonstrated for NCX_Mj (TC# 2.A.19.5.3).  The inward facing conformation has a "hydrophobic seal" that closes the external exit.

Firmicutes

YfkE of Bacillus subtilis
2.A.17.3.1









High affinity (~0.1 μM) Nitrate/Chlorate symporter, Nrt1.1; CHL1 (Martin et al., 2008)

Plants
CHL1 of Arabidopsis thaliana
2.A.17.3.2









Histidine or peptide:H+ symporter
Plants
PTR2-B (NTR1) of Arabidopsis thaliana
2.A.17.3.3









Nitrate (chlorate) or histidine:H+ symporter
Plants
RCH2 of Brassica napus
2.A.17.3.4









Peptide transporter, PTR3-A (induced by histidine, leucine and phenylalanine in cotyledons and lower leaves; involved in stress tolerance in seeds during germination and in defense against virulent bacterial pathogens) (Karim et al., 2007; Karim et al., 2005)
Plants
PTR3-A of Arabidopsis thaliana (Q9FNL7)
2.A.17.3.5









The nitrate excretion transporter1, NaxT1 (in the plasma membranes of plant cells)
Plants
NaxT1 of Arabidopsis thaliana (Q9M1E2)
2.A.17.3.6









Chloroplast nitrite uptake system, Nitr1-L (Sugiura et al., 2007)
Plants
Nitr1-L of Arabidopsis thaliana (Q9SX20)
2.A.17.3.7









The root dipeptide/tripeptide transporter, PTRI (Komarova et al., 2008). Transport is electrogenic and dependent on protons. Leak currents are inhibited by Phe-Ala when this peptide binds at the active site with high affinity (Hammes et al., 2010).

Plants

PTR1 of Arabidopsis thaliana (Q9M390)
2.A.17.3.8









The germinating pollen dipeptide/tripeptide transporter, PTR5 (Komarova et al., 2008). Transport is electrogenic and dependent on protons. Leak currents are inhibited by Phe-Ala when this peptide binds at the active site with high affinity (Hammes et al., 2010).

Plants

PTR5 of Arabidopsis thaliana (Q0WR84)
2.A.17.3.9









solute carrier family 15, member 3
Animals
SLC15A3 of Homo sapiens
2.A.17.3.10









solute carrier family 15, member 5
Animals
SLC15A5 of Homo sapiens
2.A.17.3.11









Solute carrier family 15 member 4 (Peptide transporter 4) (Peptide/histidine transporter 1) (hPHT1)
Animals
SLC15A4 of Homo sapiens
2.A.17.3.12









Putative peptide/nitrate transporter At3g25280
Plants
At3g25280 of Arabidopsis thaliana
2.A.17.3.13









Probable peptide transporter At1g52190
Plants
At1g52190 of Arabidopsis thaliana
2.A.17.3.14









Nitrate transporter 1.6
Plants
NRT1.6 of Arabidopsis thaliana
2.A.17.3.15









Nitrate transporter 1.7
Plants
NRT1.7 of Arabidopsis thaliana
2.A.17.3.16









Nitrate transporter 1.2 (Nitrate transporter NTL1)
Plants
NRT1.2 of Arabidopsis thaliana
2.A.17.3.17









Probable peptide/nitrate transporter At3g47960
Plants
At3g47960 of Arabidopsis thaliana
2.A.17.3.18









Nitrate transporter 1.4
Plants
NRT1.4 of Arabidopsis thaliana
2.A.17.3.19









Nitrate transporter 1.5
Plants
NRT1.5 of Arabidopsis thaliana
2.A.17.4.1









Peptide:H+ symporter (transports cationic, neutral and anionic dipeptides including glycylsarcosine (gly-sar) (Søndergaard et al., 2008) as well as anserine (β-alanyl-1-N-methyl-L-histidine) and carnosine (β-alanyl-L-histidine) (Geissler et al., 2010); also transports β-lactam antibiotics, the antitumor agent, bestatin, and various protease inhibitors). It is competitively inhibited by L-4,4'-biphenylalanyl-L-proline (Bip-Pro) with ~10-20µM affinity. Inhibitors/substrates include cefadroxil, Ala-4-nitroanilide and δ-aminolevulinic acid (Knutter et al., 2007). The intracellular loop linking transmembrane domains 6 and 7 of the human dipeptide transporter hPEPT1 includes two amphipathic alpha-helices, with net positive and negative charges which interact and influence conformational changes of hPEPT1 during and after glycylsarcosine transport (Xu et al., 2010).

Animals

PepT1 of Rattus norvegicus
2.A.17.4.2









Oligopeptide transporter 1
Animals
Oligopeptide transporter of Drosophila melanogaster
2.A.17.4.3









High affinity oligopeptide transporter, CPTA (transports di-, tri- and tetra peptides with low specificity. Neuropeptides (FMRF-amide and N-acetyl-Asp-Glu) are also transported)
Animals
CPTA of Caenorhabditis elegans
2.A.17.4.4









The renal brush-border electrogenic, proton-coupled, broad specificity, high affinity, peptide transporter, PepT2 (Rubio-Aliaga et al., 2000). It is competitively inhibited by L-4,4'-Biphenylalanyl-L-Proline (Bip-Pro) with ~10-20ÁM affinity. Inhibitor/substrates includes cefadroxil, Ala-4-nitroanilide and delta-aminolevulinic acid (Knutter et al., 2007).
Animals
PepT2 of Mus musculus (Q9ES07)
2.A.17.4.5









The high affinity, low capacity, peptide transporter, PepT2 (SLC15A2) [affinity for glycyl-L-glutamine=18μM] (Romano et al., 2006)
Animals
PepT2 of Danio rerio (NP_0010349)
2.A.17.4.6









Oligopeptide transporter, PepT1 (Slc15A1b) (Bucking and Schulte, 2012) (expressed in freshwater acclimated fish)

Animals

PepT1b of Fundulus heteroclitus (H2DJV9)
2.A.17.4.7









Di-/Tri-peptide porter. 3-d structure (PDB: 2XUT) known revealing a probable alternating access mechanism of transport (Newstead et al., 2011).  A second structure shows the protein in an inward open conformation with the peptidommetic, alafosfalin, bound (Guettou et al. 2013).

Bacteria

Di-/Tri-peptide permease of Shewanella oneidensis (Q8EKT7)
2.A.17.4.8









Solute carrier family 15 member 2 (Kidney H(+)/peptide cotransporter) (Oligopeptide transporter, kidney isoform) (Peptide transporter 2)
Animals
SLC15A2 of Homo sapiens
2.A.17.4.9









Solute carrier family 15 member 1 (Intestinal H(+)/peptide cotransporter) (Oligopeptide transporter, small intestine isoform) (Peptide transporter 1)
Animals
SLC15A1 of Homo sapiens
2.A.17.4.10









Peptide transporter 3 (Oligopeptide transporter 3)
Worm
Pept-3 of Caenorhabditis elegans