Obligatory Amino Acid Exchange via Systems bo,+-like and y+L-like

Josep Chillarón, Raúl Estévez, Conchi Mora, Carsten A. Wagner, Hartmut Suessbrich, Florian Lang, Josep Lluís Gelpí, Xavier Testar, Andreas E. Busch, Antonio Zorzano, Manuel Palacín
1996 Journal of Biological Chemistry  
Mutations in the rBAT gene cause type I cystinuria, a common inherited aminoaciduria of cystine and dibasic amino acids due to their defective renal and intestinal reabsorption (Calonge, M. A. 92, 9667-9671). One important question that remains to be clarified is how the apparently non-concentrative system b o,؉ -like, associated with rBAT expression, participates in the active renal reabsorption of these amino acids. Several studies have demonstrated exchange of amino acids induced by rBAT in
more » ... enopus oocytes. Here we offer evidence that system b o,؉ -like is an obligatory amino acid exchanger in oocytes and in the "renal proximal tubular" cell line OK. System b o,؉ -like showed a 1:1 stoichiometry of exchange, and the hetero-exchange dibasic (inward) with neutral (outward) amino acids were favored in oocytes. Obligatory exchange of amino acids via system b o,؉ -like fully explained the amino acid-induced current in rBAT-injected oocytes. Exchange via system b o,؉ -like is coupled enough to ensure a specific accumulation of substrates until the complete replacement of the internal oocyte substrates. Due to structural and functional analogies of the cell surface antigen 4F2hc to rBAT, we tested for amino acid exchange via system y ؉ L-like. 4F2hc-injected oocytes accumulated substrates to a level higher than CAT1-injected oocytes (i.e. oocytes expressing system y ؉ ) and showed exchange of amino acids with the substrate specificity of system
doi:10.1074/jbc.271.30.17761 pmid:8663357 fatcat:3o7ze2iuord27nkmjouytktgpm