title: Characterization of mouse amino acid transporter B0AT1 (slc6a19).
abstract: The mechanism of the mouse (m)B0AT1 (slc6a19) transporter was studied in detail using two electrode voltage-clamp techniques and tracer studies in the Xenopus oocyte expression system. All neutral amino acids induced inward currents at physiological potentials, but large neutral non-aromatic amino acids were the preferred substrates of mB0AT1. Substrates were transported with K0.5 values ranging from approx. 1 mM to approx. 10 mM. The transporter mediates Na+-amino acid co-transport with a stoichiometry of 1:1. No other ions were involved in the transport mechanism. An increase in the extracellular Na+ concentration reduced the K0.5 for leucine, and vice versa. Moreover, the K0.5 values and Vmax values of both substrates varied with the membrane potential. As a result, K0.5 and Vmax values are a complex function of the concentration of substrate and co-substrate and the membrane potential. A model is presented assuming random binding order and a positive charge associated with the ternary [Na+-substrate-transporter] complex, which is consistent with the experimental data.
authors.affiliation: Physiologisches Institut, Universität Tübingen, 72076 Tübingen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Böhmer
authors.forename: Angelika
authors.initials: A
authors.lastname: Bröer
authors.forename: Michael
authors.initials: M
authors.lastname: Munzinger
authors.forename: Sonja
authors.initials: S
authors.lastname: Kowalczuk
authors.forename: John E J
authors.initials: JE
authors.lastname: Rasko
authors.forename: Florian
authors.initials: F
authors.lastname: Lang
authors.forename: Stefan
authors.initials: S
authors.lastname: Bröer
mesh_terms: D026905:Amino Acid Transport Systems / Q000737:chemistry* / Q000378:metabolism*; D026921:Amino Acid Transport Systems, Neutral / Q000737:chemistry / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active; D007700:Kinetics; D008564:Membrane Potentials; D051379:Mice; D009865:Oocytes; D013379:Substrate Specificity; D014981:Xenopus
chemical_list: D026905:Amino Acid Transport Systems; D026921:Amino Acid Transport Systems, Neutral; D000596:Amino Acids; C505021:SLC6A19 protein, mouse