FEBS Lett 2002 Sep 11;5271-3:125-32. doi: 10.1016/s0014-5793(02)03194-0.

Differential effect of pH on sodium binding by the various GABA transporters expressed in Xenopus oocytes.

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Mouse GABA transporters belong to the family of Na(+)- and Cl(-)-dependent neurotransmitter transporters. The four GABA transporters exhibit unique presteady-state currents when expressed in Xenopus oocytes. The properties of the presteady-state currents correspond to their different affinities to Na(+). In the presence of 20 microM GABA and at pH 7.5, the half-maximal uptake activity was 47, 120, 25 and 35 mM Na(+) for GAT1, GAT2, GAT3 and GAT4, respectively. The appearance of presteady-state currents at positive or negative imposed potentials was in correlation with the affinity to Na(+). Changing the external pH differentially affected the GABA uptake and the presteady-state activities of the various GABA transporters. It is suggested that protons compete with Na(+) on its binding site; however, the proton binding is not productive and is unable to drive GABA uptake.

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Species referenced: Xenopus
Genes referenced: slc6a1 slc6a11 slc6a13