Different anesthetic sensitivities of skeletal and cardiac isoforms of the Ca-ATPase.
Different anesthetic sensitivities of skeletal and cardiac isoforms of the Ca-ATPase.
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Ca-ATP 酶的骨骼和心脏异构体的不同麻醉敏感性。
DOI：
10.1021/bi990190u
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Thomas,DD
中科院分区：
文献类型：
--
作者：
Karon,BS;Autry,JM;Shi,Y;Garnett,CE;Inesi,G;Jones,LR;Kutchai,H;Thomas,DD
我们以前已经表明，低水平的挥发性麻醉剂氟烷激活骨骼肌浆网（SR）中的Ca-ATP酶，但抑制心脏SR中的Ca-ATP酶。在这项研究中，我们询问这种差异性抑制是否是由于（a）心脏SR中存在调节蛋白受磷蛋白，（B）骨骼肌和心脏SR中不同的脂质环境，或（c）存在于两种组织中的不同Ca-ATP酶同种型。通过在Sf 21昆虫细胞器中表达钙ATP酶的骨骼（SERCA 1）和心脏（SERCA 2a）异构体，我们发现骨骼和心脏SR中的不同麻醉作用是由于SERCA 1和SERCA 2a异构体对麻醉剂的不同敏感性。低水平的氟烷抑制Ca-ATP酶的SERCA 2a亚型，而对SERCA 1亚型几乎没有影响。氟烷抑制的生化机制涉及Ca-ATP酶的E2构象的稳定，表明与ATP酶的直接麻醉相互作用。本研究建立了麻醉剂对膜蛋白作用机制的生物化学模型，并将导致对Ca-ATP酶的SERCA 1和SERCA 2a亚型上的麻醉剂结合位点的鉴定。
We have previously shown that low levels of the volatile anesthetic halothane activate the Ca-ATPase in skeletal sarcoplasmic reticulum (SR), but inhibit the Ca-ATPase in cardiac SR. In this study, we ask whether the differential inhibition is due to (a) the presence of the regulatory protein phospholamban in cardiac SR, (b) different lipid environments in skeletal and cardiac SR, or (c) the different Ca-ATPase isoforms present in the two tissues. By expressing skeletal (SERCA 1) and cardiac (SERCA 2a) isoforms of the Ca-ATPase in Sf21 insect cell organelles, we found that differential anesthetic effects in skeletal and cardiac SR are due to differential sensitivities of the SERCA 1 and SERCA 2a isoforms to anesthetics. Low levels of halothane inhibit the SERCA 2a isoform of the Ca-ATPase, and have little effect on the SERCA 1 isoform. The biochemical mechanism of halothane inhibition involves stabilization of E2 conformations of the Ca-ATPase, suggesting direct anesthetic interaction with the ATPase. This study establishes a biochemical model for the mechanism of action of an anesthetic on a membrane protein, and should lead to the identification of anesthetic binding sites on the SERCA 1 and SERCA 2a isoforms of the Ca-ATPase.