Chicken skeletal muscle ryanodine receptor isoforms: ion channel properties.
Chicken skeletal muscle ryanodine receptor isoforms: ion channel properties.
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鸡骨骼肌兰尼碱受体亚型：离子通道特性。
DOI：
10.1016/s0006-3495(94)80665-4
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发表时间：
1994
影响因子：
3.4
通讯作者：
Sutko,JL
中科院分区：
文献类型：
--
作者：
Percival,AL;Williams,AJ;Kenyon,JL;Grinsell,MM;Airey,JA;Sutko,JL
为了确定鸡骨骼肌中表达的 α- 和 β-ryanodine 受体 (RyR)（肌浆网 Ca2+ 释放通道）亚型的作用，我们研究了这些蛋白质在脂质双层中的离子通道特性。 α-和β RyR 体现的 Ca2+ 通道具有相似的电导（K+、Cs+ 和 Ca2+ 为 792、453 和 118 pS）和选择性（PCa2+/PK+ = 7.4），但两个通道具有不同的门控特性。 α RyR 通道在两种门控模式之间切换，这两种门控模式的不同之处在于它们被 Ca2+ 和 ATP 激活以及被 Ca2+ 灭活的程度。任何一种模式都可以以自发且稳定的方式呈现。在低活性模式下，α RyR 通道表现出短暂的开放（tau o = 0.14 ms），并且在没有 ATP 的情况下被 Ca2+ 最小程度地激活。在高活性模式下，开口更长（tau o1–3 = 0.17、0.51 和 1.27 ms），并且通道在没有 ATP 的情况下被 Ca2+ 激活，并且通常对 Ca2+ 的失活作用不太敏感。在任一模式下，β RyR 通道的开口都比 α RyR 通道的开口更长（tau 01–3 = 0.34、1.56 和 3.31 ms）。与 ATP 相比，β RyR 通道被 Ca2+ 激活的相对程度更大，并且在 ATP 不存在（而非存在）的情况下被毫摩尔 Ca2+ 灭活。 α- 和 β RyR 通道均被咖啡因激活，被 Mg2+ 和钌红抑制，被电压灭活（细胞质侧阳性），并被兰尼定修饰为长寿命亚状态，但只有 α RyR 通道被高氯酸盐阴离子激活。门控和对通道调节剂反应的差异可能使 α- 和 β RyR 在肌肉激活中发挥不同的作用。
To define the roles of the alpha- and beta-ryanodine receptor (RyR) (sarcoplasmic reticulum Ca2+ release channel) isoforms expressed in chicken skeletal muscles, we investigated the ion channel properties of these proteins in lipid bilayers. alpha- and beta RyRs embody Ca2+ channels with similar conductances (792, 453, and 118 pS for K+, Cs+ and Ca2+) and selectivities (PCa2+/PK+ = 7.4), but the two channels have different gating properties. alpha RyR channels switch between two gating modes, which differ in the extent they are activated by Ca2+ and ATP, and inactivated by Ca2+. Either mode can be assumed in a spontaneous and stable manner. In a low activity mode, alpha RyR channels exhibit brief openings (tau o=0.14 ms) and are minimally activated by Ca2+ in the absence of ATP. In a high activity mode, openings are longer (tau o1–3 = 0.17, 0.51, and 1.27 ms), and the channels are activated by Ca2+ in the absence of ATP and are in general less sensitive to the inactivating effects of Ca2+. beta RyR channel openings are longer (tau 01–3 = 0.34, 1.56, and 3.31 ms) than those of alpha RyR channels in either mode. beta RyR channels are activated to a greater relative extent by Ca2+ than ATP and are inactivated by millimolar Ca2+ in the absence, but not the presence, of ATP. Both alpha- and beta RyR channels are activated by caffeine, inhibited by Mg2+ and ruthenium red, inactivated by voltage (cytoplasmic side positive), and modified to a long-lived substate by ryanodine, but only alpha RyR channels are activated by perchlorate anions. The differences in gating and responses to channel modifiers may give the alpha- and beta RyRs distinct roles in muscle activation.