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首页> 外文期刊>American Journal of Physiology >RyR1 exhibits lower gain of CICR activity than RyR3 in the SR: evidence for selective stabilization of RyR1 channel.
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RyR1 exhibits lower gain of CICR activity than RyR3 in the SR: evidence for selective stabilization of RyR1 channel.

机译：在SR中，RyR1展示的CICR活性低于RyR3：表明RyR1通道选择性稳定的证据。

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摘要

We showed that frog alpha-ryanodine receptor (alpha-RyR) had a lower gain of Ca(2+)-induced Ca(2+) release (CICR) activity than beta-RyR in sarcoplasmic reticulum (SR) vesicles, indicating selective "stabilization" of the former isoform (Murayama T and Ogawa Y. J Biol Chem 276: 2953-2960, 2001). To know whether this is also the case with mammalian RyR1, we determined [(3)H]ryanodine binding of RyR1 and RyR3 in bovine diaphragm SR vesicles. The value of [(3)H]ryanodine binding (B) was normalized by the number of maximal binding sites (B(max)), whereby the specific activity of each isoform was expressed. This B/B(max) expression demonstrated that ryanodine binding of individual channels for RyR1 was <15% that for RyR3. Responses to Ca(2+), Mg(2+), adenine nucleotides, and caffeine were not substantially different between in situ and purified isoforms. These results suggest that the gain of CICR activity of RyR1 is markedly lower than that of RyR3 in mammalian skeletal muscle, indicating selective stabilization of RyR1 as is true of frog alpha-RyR. The stabilization was partly eliminated by FK506 and partly by solubilization of the vesicles with CHAPS, each of which was additive to the other. In contrast, high salt, which greatly enhances [(3)H]ryanodine binding, caused only a minor effect on the stabilization of RyR1. None of the T-tubule components, coexisting RyR3, or calmodulin was the cause. The CHAPS-sensitive intra- and intermolecular interactions that are common between mammalian and frog skeletal muscles and the isoform-specific inhibition by FKBP12, which is characteristic of mammals, are likely to be the underlying mechanisms.
机译：我们显示，青蛙α-ryanodine受体（alpha-RyR）比肌浆网（SR）囊泡中的beta-RyR具有更低的Ca（2+）诱导的Ca（2+）释放（CICR）活性，表明选择性“稳定性”（Murayama T和Ogawa Y. J Biol Chem 276：2953-2960，2001）。要知道哺乳动物RyR1是否也是这种情况，我们确定了牛diaphragm SR囊泡中RyR1和RyR3的[（3）H] ryanodine结合。通过最大结合位点数（B（max））将[（3）H] ryanodine结合（B）的值归一化，从而表达每种同工型的比活性。此B / B（max）表达表明，RyR1的各个通道的瑞丹定结合率小于RyR3的15％。对Ca（2 +），Mg（2+），腺嘌呤核苷酸和咖啡因的反应在原位和纯化的同工型之间没有显着差异。这些结果表明，在哺乳动物骨骼肌中，RyR1的CICR活性的获得显着低于RyR3，这表明RyR1的选择性稳定，就像青蛙alpha-RyR一样。 FK506消除了部分稳定作用，而部分囊泡则通过CHAPS增溶，CHAPS中的每一种都是彼此加成的。相反，高盐会极大地增强[（3）H] ryanodine的结合，对RyR1的稳定作用只产生很小的影响。 T管成分，共存的RyR3或钙调蛋白都不是原因。哺乳动物和青蛙骨骼肌之间常见的CHAPS敏感分子内和分子间相互作用以及哺乳动物特征性的FKBP12抑制同工型特异性，可能是其潜在机制。

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