title: Transport of L-cysteine by rat renal brush border membrane vesicles.
abstract: Brush border membranes were isolated from rat renal cortex by a divalent cation precipitation method. L-35S-cysteine uptake into the vesicles was measured by a rapid filtration method. Only minimal binding of the amino acid to the vesicles was observed. Sodium stimulates L-cysteine uptake specifically. Anion replacement experiments, experiments in the presence of potassium/valinomycin-induced diffusion potential as well as experiments with a potential-sensitive fluorescent dye document an electrogenic sodium-dependent uptake mechanism for L-cysteine. Tracer replacement experiments as well as the fluorescence experiments indicate a preferential transport of L-cysteine. Transport of L-cysteine is inhibited by L-alanine and L-phenylalanine but not by L-glutamic acid and the L-basic amino acids. Initial, linear influx kinetics provide evidence for the existence of two transport sites. The results suggest (a) sodium-dependent mechanism(s) for L-cysteine shared by other neutral amino acids.
mesh_terms: D000409:Alanine / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002474:Cell-Free System; D003545:Cysteine / Q000378:metabolism*; D003553:Cystine / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism; D051381:Rats; D012964:Sodium / Q000502:physiology; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds
chemical_list: D013438:Sulfhydryl Compounds; D010649:Phenylalanine; D003553:Cystine; D012964:Sodium; D003545:Cysteine; D000409:Alanine