Bohmer, ChristophBroer, AngelikaKingsland (previously Munzinger), MichaelKowalczuk, SonjaRasko, John EdwardLang, FlorianBroer, Stefan2015-12-130264-6021http://hdl.handle.net/1885/82072The 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 K 0.5 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.Keywords: Biological membranes; Electrodes; Ions; Mathematical models; Stoichiometry; Amino acid transport; Hartnup disorder; Neurotransmitter transporter family; Transport mechanism; Amino acids; alanine; amino acid; amino acid transporter; carbon 14; glutamine; g Amino acid transport; Hartnup disorder; Neurotransmitter transporter family; Transport mechanism200510.1042/BJ200500832015-12-11