Steady states, charge movements, and rates for a cloned GABA transporter expressed in Xenopus oocytes

Neuron. 1993 Feb;10(2):177-88. doi: 10.1016/0896-6273(93)90309-f.


Voltage-clamp analysis was applied to study the currents associated with the uptake of extracellular gamma-aminobutyric acid (GABA) by the cloned transporter GAT1 expressed at high efficiency in Xenopus oocytes. Steady-state GABA currents were increased at higher extracellular [GABA], [Na+], and [Cl-] and at more negative potentials. The Hill coefficient for Na+ exceeded unity, suggesting the involvement of two Na+ ions. In the absence of GABA, voltage jumps produced transient currents that behaved like capacitive charge movements; these were suppressed by the uptake inhibitor SKF-89976A, were shifted to more negative potentials at lower external [Na+] and [Cl-], and had an effective valence of 1.1 elementary charge. A turnover rate per transporter of 6-13/s at maximal [GABA] (-80 mV, 96 mM NaCl, 22 degrees C) is given both by the kinetics of voltage jump relaxations and by the ratio between the maximal GABA currents and the charge movements. These quantitative data are necessary for evaluating the roles of GAT1 in synaptic function.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carrier Proteins / genetics
  • Carrier Proteins / physiology*
  • Cell Membrane / physiology
  • Chlorides / pharmacology
  • Cloning, Molecular*
  • Electric Conductivity
  • Electrophysiology
  • Female
  • GABA Antagonists
  • GABA Plasma Membrane Transport Proteins
  • Gene Expression
  • Kinetics
  • Membrane Proteins / genetics
  • Membrane Proteins / physiology*
  • Membrane Transport Proteins*
  • Nipecotic Acids / pharmacology
  • Oocytes / metabolism*
  • Oocytes / physiology
  • Organic Anion Transporters*
  • RNA / genetics
  • RNA, Complementary
  • Sodium / pharmacology
  • Transfection
  • Xenopus
  • gamma-Aminobutyric Acid / metabolism
  • gamma-Aminobutyric Acid / pharmacology


  • Carrier Proteins
  • Chlorides
  • GABA Antagonists
  • GABA Plasma Membrane Transport Proteins
  • Membrane Proteins
  • Membrane Transport Proteins
  • Nipecotic Acids
  • Organic Anion Transporters
  • RNA, Complementary
  • gamma-Aminobutyric Acid
  • RNA
  • N-(4,4-diphenyl-3-butenyl)nipecotic acid
  • Sodium