GABAA receptor-associated protein regulates GABAA receptor cell-surface number in Xenopus laevis oocytes
GABAA receptor-associated protein regulates GABAA receptor cell-surface number in Xenopus laevis oocytes
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DOI：
10.1124/mol.104.009878
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发表时间：
2005-07-01
影响因子：
3.6
通讯作者：
Olsen, RW
中科院分区：
文献类型：
--
作者：
Chen, ZW;Chang, CSS;Olsen, RW
GABA（A）受体相关蛋白（GABARAP）是以前在酵母双杂交筛选中分离的，使用GABA（A）受体γ 2亚基的细胞内环作为诱饵。GABARAP已被证明参与GABA（A）受体的膜聚集和细胞内运输，包括刺激GABA（A）受体的表面表达。为了定量评估这一点，我们使用表达含α 1 β 2 γ 2S的GABA（A）受体的非洲爪蟾卵母细胞来证明GABARAP的共表达增加了GABA（A）受体的净表面水平，如增加的GABA电流和表面表达的蛋白质所示。GABA电流的GABARAP刺激需要受体γ 2亚基和全长GABARAP：删除微管结合结构域（氨基酸1 - 22）或破坏微管的聚合消除了增强，表明GABARAP的作用来自与微管的相互作用。GABARAP共表达并没有改变GABA（A）受体的一般特性，如对GABA或苯二氮卓类药物的敏感性，但它增加了卵母细胞中受体蛋白的表面水平。相反，它似乎补充了不足量的内源性GABARAP，以支持表面GABA（A）受体的最佳运输和/或稳定。
GABA(A) receptor-associated protein (GABARAP) was isolated previously in a yeast two-hybrid screen using the intracellular loop of the gamma 2 subunit of the GABA(A) receptor as bait. GABARAP has been shown to participate in the membrane-clustering and intracellular-trafficking of GABA(A) receptors, including a stimulation of the surface expression of GABA(A) receptors. To assess this quantitatively, we used Xenopus laevis oocytes expressing alpha 1 beta 2 gamma 2S-containing GABA(A) receptors to demonstrate that coexpression of GABARAP increased net surface levels of GABA(A) receptors as shown by both increased GABA currents and surface-expressed protein. This GABARAP stimulation of GABA currents required the receptor gamma 2 subunit and full-length GABARAP: deletion of the microtubule-binding domain ( amino acids 1 - 22) or disrupting the polymerization of microtubules abolished the enhancement, indicating that the effect of GABARAP was derived from the interaction with microtubules. GABARAP coexpression did not alter the general properties of GABA(A) receptors such as sensitivity to GABA or benzodiazepines, but it increased surface levels of receptor protein in oocytes. Rather, it seems to supplement inadequate amounts of endogenous GABARAP to support optimum trafficking and/or stabilization of surface GABA(A) receptors.