Differential interactions of the C terminus and the cytoplasmic I-II loop of neuronal Ca2+ channels with G-protein α and βγ subunits -: II.: Evidence for direct binding
Differential interactions of the C terminus and the cytoplasmic I-II loop of neuronal Ca2+ channels with G-protein α and βγ subunits -: II.: Evidence for direct binding
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DOI：
10.1074/jbc.273.28.17595
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发表时间：
1998-07-10
影响因子：
4.8
通讯作者：
Nukada, T
中科院分区：
文献类型：
--
作者：
Furukawa, T;Miura, R;Nukada, T
本研究旨在利用来自环1(重复I和II之间的细胞质环)和这些通道的C末端的合成肽和融合蛋白，获得G蛋白α(Gα)和β伽马亚基(Gβ伽马)与N-(α(1B))和P/Q型(α(1A))钙通道直接相互作用的证据。对于N型，当细胞内应用合成的环1肽时，由Gβ伽马介导的脉冲前促进作用受到损害。受体激动剂对Gα介导的N型抑制也可被环1肽削弱，但仅当与C端肽联合使用时。相反，对于P/Q型通道，单独应用C端肽可减弱Gα介导的抑制作用。此外，N型和P/Q型通道的体外结合分析表明，Gα与C端融合蛋白直接相互作用，Gβγ与环状1融合蛋白直接相互作用。这些发现将N型和P/Q型钙通道的环1定义为Gβ伽马的相互作用部位和Gα的C末端。
The present study was designed to obtain evidence for direct interactions of G-protein alpha (G alpha) and beta gamma subunits (G beta gamma) with N- (alpha(1B)) and P/Q-type (alpha(1A)) Ca2+ channels, using synthetic peptides and fusion proteins derived from loop 1 (cytoplasmic loop between repeat I and II) and the C terminus of these channels. For N-type, prepulse facilitation as mediated by G beta gamma was impaired when a synthetic loop 1 peptide was applied intracellulary. Receptor agonist-induced inhibition of N-type as mediated by G alpha was also impaired by the loop 1 peptide but only when applied in combination with a C-terminal peptide. For P/Q-type channels, by contrast, the G alpha-mediated inhibition was diminished by application of a C-terminal peptide alone. Moreover, in vitro binding analysis for N- and P/Q-type channels revealed direct interaction of G alpha with C-terminal fusion proteins as well as direct interaction of G beta gamma with loop 1 fusion proteins. These findings define loop 1 of N- and P/Q-type Ca2+ channels as an interaction site for G beta gamma and the C termini for G alpha.