Electrogenic uptake of gamma-aminobutyric acid by a cloned transporter expressed in Xenopus oocytes. |
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Authors: | M P Kavanaugh J L Arriza R A North S G Amara |
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Institution: | Vollum Institute, Oregon Health Sciences University, Portland 97201. |
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Abstract: | GAT-1, a gamma-aminobutyric acid (GABA) transporter cloned from rat brain, was expressed in Xenopus oocytes. Voltage-clamp measurements showed concentration-dependent, inward currents in response to GABA (K0.5 4.7 microM). The transport current required extracellular sodium and chloride ions; the Hill coefficient for chloride was 0.7, and that for sodium was 1.7. Correlation of current and 3H]GABA uptake measurements indicate that flux of one positive charge occurs per molecule of GABA transported. Membrane hyperpolarization from -40 to -100 mV increased the transport current approximately 3-fold. The results indicate that the transport of one molecule of GABA involves the co-transport of two sodium ions and one chloride ion. |
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