Calmidazolium and compound 48/80 inhibit calmodulin-dependent protein phosphorylation and ATP-dependent Ca2+ uptake but not Ca2+-ATPase activity in skeletal muscle sarcoplasmic reticulum.
Calmidazolium and compound 48/80 inhibit calmodulin-dependent protein phosphorylation and ATP-dependent Ca2+ uptake but not Ca2+-ATPase activity in skeletal muscle sarcoplasmic reticulum.
复制标题
Calmidazolium 和化合物 48/80 抑制钙调素依赖性蛋白磷酸化和 ATP 依赖性 Ca2+ 摄取，但不抑制骨骼肌肌浆网中的 Ca2+-ATPase 活性。
DOI：
10.1016/s0021-9258(17)39825-3
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
D. Maclennan
中科院分区：
文献类型：
--
作者：
B. Tuana;D. Maclennan
两种特异性钙调素拮抗剂，化合物48/80和卡咪唑，浓度分别为10-20微克/毫升和10-20微克/毫升时，抑制骨骼肌肌浆网囊泡Ca2+摄取，而不影响Ca2+- atp酶活性。这些药物还能抑制85,000、60,000和20,000道尔顿蛋白的钙调素依赖性磷酸化，但不能抑制其他肌浆网蛋白的钙调素非依赖性磷酸化。60000道尔顿蛋白磷酸化的抑制与Ca2+摄取的抑制密切相关。当浓度达到抑制剂量的5倍时，两种药物都不影响肌浆网膜的被动通透性，两种药物都不抑制Ca2+摄取到用纯化的Ca2+- atp酶重组的脂质体中。然而，钙调素依赖性重构Ca2+摄取在egta提取的肌浆网囊中被48/80抑制。本研究结果表明，钙调素依赖性磷酸化系统在ATP水解和Ca2+积累的偶联中发挥功能作用，可能通过调节肌浆网膜中Ca2+释放通道。48/80和卡咪唑对磷酸化的扰动可能导致Ca2+释放增强，从而减少Ca2+积累，而不影响Ca2+摄取机制。
Two specific calmodulin antagonists, compound 48/80 and calmidazolium , at concentrations of 10-20 micrograms/ml and 10-20 microM, respectively, inhibited Ca2+ uptake in skeletal muscle sarcoplasmic reticulum vesicles without affecting Ca2+-ATPase activity. The drugs also inhibited the calmodulin-dependent phosphorylation of 85,000-, 60,000-, and 20,000-dalton proteins, but not the calmodulin-independent phosphorylation of other sarcoplasmic reticulum proteins. The inhibition of phosphorylation of the 60,000-dalton protein closely paralleled the inhibition of Ca2+ uptake. Neither drug affected the passive permeability of the sarcoplasmic reticulum membrane at concentrations up to 5 times the inhibitory dose, and neither drug inhibited Ca2+ uptake into liposomes reconstituted with the purified Ca2+-ATPase. However, calmodulin-dependent reconstitution of Ca2+ uptake in EGTA-extracted sarcoplasmic reticulum vesicles was inhibited by 48/80. The results of this study suggest that the calmodulin-dependent phosphorylation system plays a functional role in the coupling of ATP hydrolysis and Ca2+ accumulation, perhaps through regulation of Ca2+ release channels in the sarcoplasmic reticulum membrane. Perturbation of phosphorylation by 48/80 and calmidazolium may lead to enhanced Ca2+ release, thereby diminishing Ca2+ accumulation without affecting the Ca2+ uptake mechanism.