Olcese R, Qin N, Schneider T, Neely A, Wei X, Stefani E, Birnbaumer L
Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030.
Neuron. 1994 Dec;13(6):1433-8. doi: 10.1016/0896-6273(94)90428-6.
There is molecular diversity in both alpha 1 and beta subunits of voltage-gated Ca2+ channels. Coupling between voltage sensing and pore opening of the C-type alpha 1 (alpha 1c) is improved by the type 2 beta subunit (beta 2), and E-type alpha 1 beta complexes inactivate at different rates depending on the nature of beta. We compared the effects of type 1 and 2 beta subunits on activation of the human E-type alpha 1 (alpha 1E) with the effects they have on inactivation, as seen in Xenopus oocytes. The beta subtypes stimulated activation in similar fashion but affected inactivation differently, and even in opposing directions. beta subunits have a common central core but differ in their N- and C-termini and in a central region. N-terminal chimeras between beta 1 and beta 2 subunits that have opposing effects on inactivation resulted in the reciprocal transfer of their effects. We conclude that regulation of activation and inactivation of alpha 1 by beta are separable events and that the N-terminus of beta is one of the structural determinants important in setting the rate and voltage at which an alpha 1 inactivates.
电压门控性Ca2+通道的α1和β亚基均存在分子多样性。2型β亚基（β2）可改善C型α1（α1c）电压感应与孔道开放之间的偶联，并且E型α1β复合物的失活速率因β亚基的性质而异。我们在非洲爪蟾卵母细胞中比较了1型和2型β亚基对人E型α1（α1E）激活的影响以及它们对失活的影响。β亚型以相似的方式刺激激活，但对失活的影响不同，甚至方向相反。β亚基有一个共同的中央核心，但它们的N端和C端以及一个中央区域有所不同。对失活有相反作用的β1和β2亚基之间的N端嵌合体导致了它们效应的相互转移。我们得出结论，β亚基对α1激活和失活的调节是可分离的事件，并且β亚基的N端是决定α1失活速率和电压的重要结构决定因素之一。
