Identification of critical residues controlling G protein-gated inwardly rectifying K+ channel activity through interactions with the βγ subunits of G proteins
Identification of critical residues controlling G protein-gated inwardly rectifying K+ channel activity through interactions with the βγ subunits of G proteins
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DOI：
10.1074/jbc.m104851200
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发表时间：
2002-02-22
影响因子：
4.8
通讯作者：
Logothetis, DE
中科院分区：
文献类型：
--
作者：
He, C;Yan, XX;Logothetis, DE
G蛋白敏感性内向整流钾（GIRK）通道通过其细胞质N-和C-末端结构域与G蛋白β-亚基的直接相互作用而被激活。通过使用生物化学和电生理学方法的组合，我们确定了最小的N-和C-末端γ-结合结构域负责刺激GIRK 4通道活性。在这些结构域中，一个N-末端残基His-64和一个C-末端残基Leu-268被证明对G β-γ介导的GIRK 4活性至关重要。此外，这些GIRK 4位点的突变显著降低了通道结构域与Goy的结合。GIRK 1中的相应残基也显示出对γ射线敏感性的关键参与。在GIRK 4/GIRK 1异聚体中，GIRK 4 His-64和Leu-268残基对Goy敏感性的贡献大于相应的GIRK 1 His-57和Leu-262残基。这些结果确定了功能上重要的通道相互作用的网站与β γ亚基的G蛋白，通道活性的关键。
G protein-sensitive inwardly rectifying potassium (GIRK) channels are activated through direct interactions of their cytoplasmic N- and C-terminal domains with the betagamma subunits of G proteins. By using a combination of biochemical and electrophysiological approaches, we identified minimal N- and C-terminal Gbetagamma-binding domains responsible for stimulation of GIRK4 channel activity. Within these domains one N-terminal residue, His-64, and one C-terminal residue, Leu-268, proved critical for Gbetagamma-mediated GIRK4 activity. Moreover, mutations at these GIRK4 sites reduced significantly binding of the channel domains to Goy. The corresponding residues in GIRK1 also showed a critical involvement in Gbetagamma sensitivity. In GIRK4/GIRK1 heteromers the GIRK4 His-64 and Leu-268 residues showed greater contributions to Goy sensitivity than did the corresponding GIRK1 His-57 and Leu-262 residues. These results identify functionally important channel interaction sites with the betagamma subunits of G proteins, critical for channel activity.