Junctin and triadin each activate skeletal ryanodine receptors but junctin alone mediates functional interactions with calsequestrin.
Junctin and triadin each activate skeletal ryanodine receptors but junctin alone mediates functional interactions with calsequestrin.
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Junctin和Triadin各自激活骨骼瑞安氨烷受体，但单独使用Junctin介导了与Calsequestin的功能相互作用。
DOI：
10.1016/j.biocel.2009.04.017
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发表时间：
2009-11
影响因子：
4
通讯作者：
Beard, Nicole A.
中科院分区：
文献类型：
--
作者：
Wei, Lan;Gallant, Esther M.;Dulhunty, Angela F.;Beard, Nicole A.
关键词：
骨骼肌中的正常Ca 2+信号传导依赖于膜相关蛋白三聚体和连接蛋白以及它们介导Ca 2+结合蛋白钙螯合蛋白和肌浆网内腔中的1型兰尼碱受体之间的功能性相互作用的能力。这种重要的机制保存细胞内的Ca 2+商店，但知之甚少。Triadin和junctin具有相似的结构，并在骨骼肌钙螯合蛋白和ryanodine受体之间的相互作用模型中集中在一起，但它们各自的作用尚未在分子水平上进行研究。我们在这里表明，纯化的骨骼ryanodine受体同样激活纯化的三醇溶蛋白或纯化的连接蛋白添加到他们的管腔侧，虽然缺乏竞争表明，蛋白质的作用在独立的网站。令人惊讶的是，triadin和junctin在骨骼钙螯合蛋白和ryanodine受体之间传递信息的能力显着不同。纯化的钙螯合蛋白抑制连接蛋白/三聚体蛋白相关或连接蛋白相关的ryanodine受体，当管腔Ca 2+从1 mM降至≤100μM时，钙螯合蛋白再相关通道复合物进一步受到抑制，与天然通道（含有内源性钙螯合蛋白/三聚体蛋白/连接蛋白）相同。与此相反，骨骼钙螯合蛋白对三聚体/ryanodine受体复合物没有影响，并且当管腔Ca 2+下降时，该复合物的通道活性增加，如在三聚体/钙螯合蛋白重新结合之前用纯化的通道所见。因此，在这种无细胞系统中，连接蛋白单独介导腔Ca 2+，骨骼钙螯合蛋白和骨骼兰尼碱受体之间的信号，并可能减少静息Ca 2+从肌浆网泄漏。我们认为，三醇溶蛋白提供了一个不同的功能，可能占主导地位，在兴奋-收缩耦合。
Normal Ca2+ signalling in skeletal muscle depends on the membrane associated proteins triadin and junctin and their ability to mediate functional interactions between the Ca2+ binding protein calsequestrin and the type 1 ryanodine receptor in the lumen of the sarcoplasmic reticulum. This important mechanism conserves intracellular Ca2+ stores, but is poorly understood. Triadin and junctin share similar structures and are lumped together in models of interactions between skeletal muscle calsequestrin and ryanodine receptors, however their individual roles have not been examined at a molecular level. We show here that purified skeletal ryanodine receptors are similarly activated by purified triadin or purified junctin added to their luminal side, although a lack of competition indicated that the proteins act at independent sites. Surprisingly, triadin and junctin differed markedly in their ability to transmit information between skeletal calsequestrin and ryanodine receptors. Purified calsequestrin inhibited junctin/triadin-associated, or junctin-associated, ryanodine receptors and the calsequestrin re-associated channel complexes were further inhibited when luminal Ca2+ fell from 1mM to ≤100μM, as seen with native channels (containing endogenous calsequestrin/triadin/junctin). In contrast, skeletal calsequestrin had no effect on the triadin/ryanodine receptor complex and the channel activity of this complex increased when luminal Ca2+ fell, as seen with purified channels prior to triadin/calsequestrin re-association. Therefore in this cell free system, junctin alone mediates signals between luminal Ca2+, skeletal calsequestrin and skeletal ryanodine receptors and may curtail resting Ca2+ leak from the sarcoplasmic reticulum. We suggest that triadin serves a different function which may dominate during excitation- contraction coupling.
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影响因子：
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作者：
COSTELLO, B;CHADWICK, C;SAITO, A;CHU, A;MAURER, A;FLEISCHER, S
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DOI：
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发表时间：
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影响因子：
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