Substrate-dependent interference of carbonic anhydrases with the glutamine transporter SNAT3-induced conductance.

摘要: The glutamine transporter SNAT3 (SLC38A3), which also transports asparagine and histidine, exchanges sodium for protons, displays a non-stoichiometrical conductance, is suppressed by the catalytic activity of carbonic anhydrase II (CAII). In this study, we show that conductance rat SNAT3, expressed in Xenopus oocytes, following co-expression with CAI, CAIII, CAIV, CAII-H64A (mutant impaired intramolecular H+ shuttling). All CA isoforms CAII mutant displayed intact although vitro studies had reported only very low CAIII CAII-H64A. CA-mediated suppression was observed, however, when glutamine, but not asparagine, substrate. We hypothesized substrate specificity action might be due to different ion selectivity induced amino acid substrates, induce currents carried and/or protons. dependent on both pH extracellular concentration asparagine; however dependence substrate, significantly greater at higher concentrations, explain difference sensitivity CAs. Given presence CAs most cells, sensing would indicated membrane potential changes.