Effect of temperature on [3H]ryanodine binding to sarcoplasmic reticulum from bullfrog skeletal muscle.
Effect of temperature on [3H]ryanodine binding to sarcoplasmic reticulum from bullfrog skeletal muscle.
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温度对[3H]ryanodine 与牛蛙骨骼肌肌浆网结合的影响。
DOI：
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发表时间：
1990
期刊：
影响因子：
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通讯作者：
H. Harafuji
中科院分区：
文献类型：
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作者：
Y. Ogawa;H. Harafuji
已有研究表明，兰尼定以开放状态与钙离子诱导的肌浆网钙释放通道结合。众所周知，兰尼定的药理作用在低温下会减弱，而咖啡因的钙释放作用在低温下会增强。为了更深入地了解钙释放的分子机制，研究了温度对兰尼定与牛蛙骨骼肌肌浆网(HFSR)重组份结合的影响。虽然钙离子是兰尼定结合所必需的，但在盐浓度与肌浆相似的反应介质中，单靠钙离子不能引起兰诺定结合。除了钙离子，咖啡因和/或β-亚甲基三磷酸(AMPOPCP)是必需的。在咖啡因和/或AMPOPCP存在下，Ryanodine在25℃的结合与钙离子依赖的钙释放活性以及抑制剂的作用密切相关。Ryanodine结合的Scatchard图给出了一条直线，表明只有一类均匀的结合位点。在0℃时，兰尼定结合率下降。Q10平均约为3。Ryanodine与Ryanodine的亲和力降低到25℃时的一半左右，最大结合位点数没有变化。Ryanodine结合的钙的表观亲和力随温度的变化与钙释放活性的变化并不总是一致的。结合的ryanodine可能处于闭塞状态，因为它在0℃下最多90小时没有解离。
It has been clarified that ryanodine binds to Ca2(+)-induced Ca release channels in the open state in sarcoplasmic reticulum. While the pharmacological action of ryanodine is known to be retarded at a low temperature, the Ca-releasing action of caffeine is potentiated at a low temperature. In order to obtain deeper insight into the molecular mechanism underlying Ca-release, the effect of temperature on ryanodine binding to the heavy fraction of sarcoplasmic reticulum (HFSR) from bullfrog skeletal muscle was examined. Although Ca2+ is indispensable for ryanodine binding, Ca2+ alone cannot cause ryanodine binding in a reaction medium of a salt concentration similar to that of the sarcoplasm. In addition to Ca2+, caffeine and/or beta,gamma-methylene adenosine triphosphate (AMPOPCP) are necessary. [3H]Ryanodine binding at 25 degrees C closely paralleled the Ca release activity in respect of the Ca2(+)-dependence in the presence of caffeine and/or AMPOPCP, and the effects of inhibitors. A Scatchard plot for ryanodine binding gave a straight linear line, indicating a single class of homogeneous binding sites. At 0 degrees C, the rate of ryanodine binding decreased. Q10 being about 3 on average. The affinity for ryanodine was reduced to about half that at 25 degrees C, with no change in the maximum number of binding sites. The temperature-dependent change in apparent affinity for Ca2+ on ryanodine binding is not always consistent with that in the case of Ca-release activity. The bound ryanodine may be in an occluded state because it did not dissociate for up to 90 h at 0 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)