title: Mechanism of transport of L-alanine by luminal-membrane vesicles from pars recta of rabbit proximal tubule.
abstract: The characteristics of renal transport of L-alanine by luminal-membrane vesicles from proximal straight tubules (pars recta) of rabbit kidney were investigated. The following picture emerges from transport studies. Two electrogenic and Na+ requiring systems confined to this region of the nephron exist for the transport of L-alanine. In addition to Na+, the transport of L-alanine was influenced by H+. However, H+ does not substitute for Na+, but instead potentiates the Na+ effect. Modification of histidyl residues of the intact luminal-membrane vesicles by diethylpyrocarbonate (DEP), completely abolished the transient renal accumulation of L-alanine. Substrate and Na+-protection experiments suggest that histidyl residues may be at or close to the active site of the L-alanine transporter in membrane vesicles from pars recta.
authors.affiliation: Institute of Medical Biochemistry, University of Aarhus, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Vorum
authors.forename: H
authors.initials: H
authors.lastname: Jessen
authors.forename: K E
authors.initials: KE
authors.lastname: Jørgensen
authors.forename: M I
authors.initials: MI
authors.lastname: Sheikh
mesh_terms: D000409:Alanine / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D001692:Biological Transport / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D006639:Histidine; D006863:Hydrogen-Ion Concentration; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D011188:Potassium / Q000494:pharmacology; D011522:Protons; D011817:Rabbits; D012964:Sodium / Q000494:pharmacology
chemical_list: D007773:Lactates; D011522:Protons; D019344:Lactic Acid; D006639:Histidine; D012964:Sodium; D005947:Glucose; D004047:Diethyl Pyrocarbonate; D000409:Alanine; D011188:Potassium