Arginine uptake through a novel cationic amino acid:K+ symporter, System R+, in brush border membrane vesicles from larval Manduca sexta midgut.
A concentrative uptake of arginine into brush border membrane vesicles (BBMV) from the midgut of Manduca sexta larvae was driven by an inwardly directed K+ gradient. The pH-dependence of the initial rate of arginine uptake between pH 7 and 10.5 paralleled the titration curve of the amino acid, suggesting that cationic arginine is the principal ionic form that is transported. In the presence of K+, at pH 7.4, arginine uptake was cis-inhibited and trans-stimulated by arginine and lysine but not by any other naturally occurring amino acids; it was also cis-inhibited by homoarginine and ornithine. Taken together, these data argue that arginine, lysine and their analogues share a cationic amino acid:K+ symporter (cotransporter), which we will designate as System R+. This novel symporter has a substrate spectrum similar to that of the uniporter, System y+, in that it accepts arginine+, lysine+, homoarginine+ and ornithine+ and rejects histidine. However, it differs from y+ in that it is cation-dependent and is almost inactive at pH 5.5.
Liu
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Department of Biology, Temple University, Philadelphia, PA 19122, USA.
Harvey
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D000818:Animals; D001120:Arginine / Q000378:metabolism* / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D002412:Cations; D006709:Homoarginine / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000648:ultrastructure; D007700:Kinetics; D007814:Larva / Q000378:metabolism; D008239:Lysine / Q000378:metabolism / Q000494:pharmacology; D018402:Manduca / Q000378:metabolism*; D008871:Microvilli / Q000378:metabolism*; D009952:Ornithine / Q000378:metabolism; D011188:Potassium / Q000494:pharmacology*
D002352:Carrier Proteins; D002412:Cations; D006709:Homoarginine; D001120:Arginine; D009952:Ornithine; D008239:Lysine; D011188:Potassium