Temperature effects on the presteady‐state and transport‐associated currents of GABA cotransporter rGAT1

FEBS Letters

Peres, Antonio¹  Forlani, Greta¹  Bossi, Elena¹  Binda, Francesca¹  Giovannardi, Stefano¹ 

[1] Laboratory of Cellular and Molecular Physiology, Department of Structural and Functional Biology, University of Insubria, Via Dunant 3, 21100 Varese, Italy

关键词: Neurotransmitter cotransport;    γ-Aminobutyric acid transporter 1;    Temperature;    rGAT1;    rat γ-aminobutyric acid transporter 1;    GABA;    γ-aminobutyric acid;   

DOI  :  10.1016/S0014-5793(02)02271-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The effects of temperature on the γ-aminobutyric acid (GABA) uptake and on the presteady-state and transport-associated currents of the GABA cotransporter, rat γ-aminobutyric acid transporter 1 (rGAT1), have been studied using heterologous oocyte expression and voltage-clamp. Increasing temperature from 15 to 30°C increased GABA uptake, diminished the maximal value of the relaxation time constant of the presteady-state currents and increased the amplitude of the current associated with the transport of GABA. The curve of the presteady-state charge versus voltage was shifted toward negative potentials by increasing the temperature, while the maximal amount of charge (Q _max) remained constant; the τ versus V curve was also negatively shifted by increasing temperatures. Analysis of the outward (α) and inward (β) rate constants as functions of temperature showed that they are affected differently, with a Q ₁₀=3.4 for α and Q ₁₀=1.5 for β. The different temperature coefficients of the rate constants account for the observed shifts. These observations are consistent with a charge moving mechanism based on a conformational change of the protein; the weaker temperature sensitivity of the inward rate constant suggests a rate-limiting diffusional component on this process.

【 授权许可】

Unknown