Peptide Transporters

Abstract

The proton-coupled oligopeptide transporters fromthe SLC15 family are integral membrane proteinsthat mediate the cellular uptake of dipeptides, tri-peptides, and peptide-like (peptidomimetic) drugs(e.g., antiviral prodrugs). Substrate movement across the membrane is coupled with proton move-ment downward and inward electrochemical gradi-ent, which (eventually) allows the transfer of smallpeptides against a substrate gradient While it iscommonly stated that this type of transportersmove their substrates uphill, note that very fre-quently, they are also involved in the movementof the substrate down a concentration gradient,e.g., when dietary peptides or oral drugs initiatetheir absorption from the intestinal lumen; due tounfavorable physicochemical properties, such ashigh polarity andflexibility, some of the physiolog-ical substrates of these transporters would hardly beefficiently absorbed by free diffusion.