Ca2+ current enhancement by alpha 2/delta and beta subunits in Xenopus oocytes: contribution of changes in channel gating and alpha 1 protein level.
Ca2+ current enhancement by alpha 2/delta and beta subunits in Xenopus oocytes: contribution of changes in channel gating and alpha 1 protein level.
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非洲爪蟾卵母细胞中 α2/δ 和 β 亚基对 Ca2 电流的增强：通道门控和 α1 蛋白水平变化的贡献。
DOI：
10.1113/jphysiol.1995.sp021029
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Dascal,N
中科院分区：
文献类型：
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作者：
Shistik,E;Ivanina,T;Puri,T;Hosey,M;Dascal,N
1.采用生化和电生理相结合的方法，研究钙通道辅助亚基增强宏观钙电流的机制。将非洲爪哇卵母细胞注射主要成孔亚基(心脏：α1C)的RNA和辅助亚基(α2/β和β2a)的不同组合的RNA。2.单通道开放概率(Po；在0 mV时测量)分别增加了约3倍、约8倍和约35倍，分别是α2/增量、β2A和α2/增量+β2A。全细胞钙通道电流由α2/β或β2 A增加约8~10倍，而α2/β+β2 A协同作用增加约1 0 0倍。膜上35S标记的α1蛋白的量不受β2 A共表达的影响，但被α2/Delta(有或无β)共表达时增加了两倍。3.我们得出结论，宏观电流的增加同样是由于质膜中α1含量的变化和Po的增加，而β2A的所有作用都是由于Po的增加。α2/β和β2/β在增加宏观电流方面的协同作用主要是由于通道门控的协同变化。
1. A combined biochemical and electrophysiological approach was used to determine the mechanism by which the auxiliary subunits of Ca2+ channel enhance the macroscopic Ca2+ currents. Xenopus oocytes were injected with RNA of the main pore‐forming subunit (cardiac: alpha 1C), and various combinations of RNAs of the auxiliary subunits (alpha 2/delta and beta 2A). 2. The single channel open probability (Po; measured at 0 mV) was increased approximately 3‐, approximately 8‐ and approximately 35‐fold by alpha 2/delta, beta 2A and alpha 2/delta+beta 2A, respectively. The whole‐cell Ca2+ channel current was increased approximately 8‐ to 10‐fold by either alpha 2/delta or beta 2A, and synergistically > 100‐fold by alpha 2/delta+beta 2A. The amount of 35S‐labelled alpha 1 protein in the plasma membrane was not changed by coexpression of beta 2A, but was tripled by coexpression of alpha 2/delta (either with or without beta). 3. We conclude that the increase in macroscopic current by alpha 2/delta is equally due to changes in amount of alpha 1 in the plasma membrane and an increase in Po, whereas all of the effect of beta 2A is due to an increase in Po. The synergy between alpha 2/delta and beta in increasing the macroscopic current is due mainly to synergistic changes in channel gating.