| POT family | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| Symbol | PTR2 | ||||||||
| Pfam | PF00854 | ||||||||
| InterPro | IPR000109 | ||||||||
| PROSITE | PDOC00784 | ||||||||
| TCDB | 2.A.17 | ||||||||
| OPM superfamily | 15 | ||||||||
| OPM protein | 2xut | ||||||||
| |||||||||
Proteins of the Proton-dependent Oligopeptide Transporter (POT) Family (also called the PTR (peptide transport) family) are found in animals, plants, yeast, archaea and both Gram-negative and Gram-positive bacteria, and are part of the major facilitator superfamily. The transport of peptides into cells is a well-documented biological phenomenon which is accomplished by specific, energy-dependent transporters found in a number of organisms as diverse as bacteria and humans. The proton-dependent oligopeptide transporter (PTR) family of proteins is distinct from the ABC-type peptide transporters and was uncovered by sequence analyses of a number of recently discovered peptide transport proteins.[1] These proteins that seem to be mainly involved in the intake of small peptides with the concomitant uptake of a proton.[2]
Function
While most members of the POT family catalyze peptide transport, one is a nitrate permease and one can transport histidine, as well as peptides. Some of the peptide transporters can also transport antibiotics. They function by proton symport, but the substrate:H+ stoichiometry is variable: the high-affinity rat PepT2 carrier catalyzes uptake of 2 and 3 H+ with neutral and anionic dipeptides, respectively, while the low affinity PepT1 carrier catalyzes uptake of one H+ per neutral peptide.[3][4]
Transport Reaction
The generalized transport reaction catalyzed by the proteins of the POT family is:
substrate (out) + H (out) → substrate (in) H+ (in)
Structure and Mechanism
The proteins are of about 450-600 amino acyl residues in length with the eukaryotic proteins in general being longer than the bacterial proteins. They exhibit 12 putative or established transmembrane α-helical spanners.
Pairs of salt bridge interactions between transmembrane helices work in tandem to orchestrate alternating access transport within the PTR family.[5] Key roles for residues conserved between bacterial and eukaryotic homologues suggest a conserved mechanism of peptide recognition and transport that in some cases has been subtly modified in individual species.
Subfamilies
Human proteins containing this domain
FP12591; PEPT1; PTR4; SLC15A1; SLC15A2; SLC15A3; SLC15A4; hPEPT1-RF;
References
- ↑ Naider F, Becker JM, Steiner HY (1995). "The PTR family: a new group of peptide transporters". Mol. Microbiol. 16 (5): 825–834. doi:10.1111/j.1365-2958.1995.tb02310.x. PMID 7476181. S2CID 46360416.
- ↑ Skurray RA, Paulsen IT (1994). "The POT family of transport proteins". Trends Biochem. Sci. 19 (10): 404. doi:10.1016/0968-0004(94)90087-6. PMID 7817396.
- ↑ Bucking, Carol; Schulte, Patricia M. (24 December 2011). "Environmental and nutritional regulation of expression and function of two peptide transporter (PepT1) isoforms in a euryhaline teleost". Comparative Biochemistry and Physiology. Part A: Molecular and Integrative Physiology. 161 (4): 379–387. doi:10.1016/J.CBPA.2011.12.008. ISSN 1095-6433. PMID 22227314. Wikidata Q34245558.
- ↑ Chen, Xing-Zhen (29 Jan 1999). "Stoichiometry and kinetics of the high-affinity H+-coupled peptide transporter PepT2". Journal of Biological Chemistry. 274 (5): 2773–2779. doi:10.1074/jbc.274.5.2773. PMID 9915809.
- ↑ Doki, Shintaro; Kato, Hideaki E.; Solcan, Nicolae; Iwaki, Masayo; Koyama, Michio; Hattori, Motoyuki; Iwase, Norihiko; Tsukazaki, Tomoya; Sugita, Yuji (2013-07-09). "Structural basis for dynamic mechanism of proton-coupled symport by the peptide transporter POT". Proceedings of the National Academy of Sciences of the United States of America. 110 (28): 11343–11348. Bibcode:2013PNAS..11011343D. doi:10.1073/pnas.1301079110. ISSN 1091-6490. PMC 3710879. PMID 23798427.
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