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Biochem J. 2005 Aug 1;389(Pt 3):745-51.

Characterization of mouse amino acid transporter B0AT1 (slc6a19).

Author information

1
Physiologisches Institut, Universität Tübingen, 72076 Tübingen, Germany.

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.

PMID:
15804236
PMCID:
PMC1180725
DOI:
10.1042/BJ20050083
[Indexed for MEDLINE]
Free PMC Article

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