title: Proton-coupled transport of organic solutes in animal cell membranes and its relation to Na+ transport.
abstract: Recent studies on proton-coupled transport of organic solutes in animal cell membranes were reviewed. In the intestinal and renal brush border membranes, transport of intact small peptides (di- or tri-peptides) has been established to be cotransported with H+. The peptide transport is Na+-independent, dependent on a pH gradient, electrogenic as revealed by transport-associated membrane depolarization and conductance increase, and reveals a marked overshoot uptake when a sufficiently large proton gradient is imposed across the membrane. Similar properties are found for L-lysine transport by the brush border membrane vesicles from mullet kidney and for L-leucine transport in some cultured cells. Partial involvement of H+ in Na+-dependent transport has also been reported for some organic acids, L-glutamate, and citrate. The physiological meanings of these purely H+-dependent and partially H+-dependent transports have been discussed based on available data.
mesh_terms: D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism*; D004151:Dipeptides / Q000378:metabolism; D006859:Hydrogen / Q000502:physiology; D007413:Intestinal Mucosa / Q000378:metabolism; D007477:Ions; D007668:Kidney / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D011522:Protons; D012964:Sodium / Q000378:metabolism*
chemical_list: D004151:Dipeptides; D007477:Ions; D011522:Protons; D006859:Hydrogen; D012964:Sodium