Ryanodine stabilizes multiple conformational states of the skeletal muscle calcium release channel.
Ryanodine stabilizes multiple conformational states of the skeletal muscle calcium release channel.
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DOI：
10.1016/s0021-9258(18)35875-7
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发表时间：
1992-11
期刊：
影响因子：
--
通讯作者：
E. Buck;I. Zimanyi;J. Abramson;I. Pessah
中科院分区：
文献类型：
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作者：
E. Buck;I. Zimanyi;J. Abramson;I. Pessah
纳摩尔至微摩尔的兰尼定改变与双层脂膜 (BLM) 融合的骨骼肌浆网 (SR) 的 Ca2+ 释放通道的门控动力学。在不对称 CsCl 和 100 microM CaCl2 顺式存在的情况下，兰尼碱 (RY) (5-40 nM) 会激活通道，增加开放概率（po；最大控制的 300%），而不改变单一电导（468 皮西 (pS)）。门控动力学的统计分析表明，打开和关闭的停留时间呈现双指数分布，并且被纳摩尔 RY 显着改变。低纳摩尔 RY 改变的通道门控动力学是完全可逆的，并且在相同的实验条件下与纳摩尔 [3H]RY 及其高亲和力位点 (Kd1 = 0.7 nM) 的结合动力学良好相关。 RY (20-50 nM) 偶尔会引起 1/2 电导波动，这与 [3H]RY 与具有较低亲和力 (Kd2 = 23 nM) 的第二个位点的结合相关。 RY (5-50 nM) 在 500 mM CsCl 存在下显着增强 Ca(2+) 诱导的 Ca2+ 从主动负载的 SR 囊泡中释放。 Ryanodine > 或 = 50 nM 可将通道稳定在 234 pS 的亚电导下，该亚电导不易可逆。 RY (> 或 = 70 microM) 产生从 1/2 到 1/4 电导波动的单向转变，而 RY > 或 = 200 microM 导致通道完全关闭。稳定 1/4 电导转变和通道闭合所需的 RY 与 [3H]RY 平衡结合常数没有定量相关性，并且归因于在 500 mM CsCl 存在下与 > 200 nM [3H]RY 的关联动力学显着降低。这些结果表明 RY 稳定了 SR 释放通道的四种离散状态，并支持通道蛋白上存在多个相互作用的 RY 效应位点。
Nanomolar to micromolar ryanodine alters the gating kinetics of the Ca2+ release channel from skeletal sarcoplasmic reticulum (SR) fused with bilayer lipid membranes (BLM). In the presence of asymmetric CsCl and 100 microM CaCl2 cis, ryanodine (RY) (5-40 nM) activates the channel, increasing the open probability (po; maximum 300% of control) without changing unitary conductance (468 picosiemens (pS)). Statistical analyses of gating kinetics reveal that open and closed dwell times exhibit biexponential distributions and are significantly modified by nanomolar RY. Altered channel gating kinetics with low nanomolar RY is fully reversible and correlates well with binding kinetics of nanomolar [3H]RY with its high affinity site (Kd1 = 0.7 nM) under identical experimental conditions. RY (20-50 nM) induces occasional 1/2 conductance fluctuations which correlate with [3H]RY binding to a second site having lower affinity (Kd2 = 23 nM). RY (5-50 nM) in the presence of 500 mM CsCl significantly enhances Ca(2+)-induced Ca2+ release from actively loaded SR vesicles. Ryanodine > or = 50 nM stabilizes the channel in a 234-pS subconductance which is not readily reversible. RY (> or = 70 microM) produces a unidirectional transition from the 1/2 to a 1/4 conductance fluctuation, whereas RY > or = 200 microM causes complete closure of the channel. The RY required for stabilizing 1/4 conductance transitions and channel closure do not quantitatively correlate with [3H]RY equilibrium binding constants and is attributed to significant reduction in association kinetics with > 200 nM [3H]RY in the presence of 500 mM CsCl. These results demonstrate that RY stabilizes four discrete states of the SR release channel and supports the existence of multiple interacting RY effector sites on the channel protein.