Evidence for a dipeptide transport system in renal brush border membranes from rabbit.
Papain treatment of renal brush border vesicles was carried out as a successful first step towards the purification of the membrane components involved in dipeptide transport. The treated vesicles exhibited increased specific transport activity of glycyl-L-proline. In contrast, the specific transport activity of L-alanine in the treated vesicles was less than that in the control vesicles. Papain treatment resulted in the solubilization of 38% of protein, 55% of alkaline phosphatase, 90% of gamma-glutamyltransferase and 95% of leucine aminopeptidase. There was no change in the intravesicular volume nor was there any increase in vesicular permeability. Glycyl-L-proline transport was Na+-independent in the control and papain-treated vesicles. Diamide reduced the Na+-dependent L-alanine transport while glycyl-L-proline transport remained unaffected in the presence of Na+. Many dipeptides inhibited glycyl-L-proline transport both in the presence and absence of Na+. The inhibition by dipeptides was greater than the inhibition by equivalent concentrations of free amino acids. These data demonstrate that renal brush border vesicles can efficiently handle dipeptides by a mechanism completely different from that of amino acid transport.
D000409:Alanine / Q000378:metabolism; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism*; D003958:Diamide / Q000494:pharmacology; D004151:Dipeptides / Q000378:metabolism* / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism*; D010206:Papain / Q000494:pharmacology; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology
D000596:Amino Acids; D004151:Dipeptides; D003958:Diamide; C015248:glycylproline; D012964:Sodium; D010206:Papain; D000409:Alanine