Temperature dependent measurements reveal similarities between muscle and non-muscle myosin motility.
Temperature dependent measurements reveal similarities between muscle and non-muscle myosin motility.
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温度依赖性测量揭示了肌肉和非肌肉肌球蛋白运动之间的相似性。
DOI：
10.1007/s10974-012-9316-7
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发表时间：
2012
影响因子：
2.7
通讯作者：
Sellers,JamesR
中科院分区：
文献类型：
--
作者：
Yengo,ChristopherM;Takagi,Yasuharu;Sellers,JamesR
我们通过体外运动和肌动蛋白激活的 ATP 酶测定检查了肌肉和非肌肉肌球蛋白（重肌球蛋白，HMM）的温度依赖性。我们的结果表明，肌球蛋白 V (MV) 具有温度依赖性，这在 ATP 酶和运动测定中是相似的。我们证明，与体外运动测定相比，骨骼肌肌球蛋白 (SK)、平滑肌肌球蛋白 (SM) 和非肌肉肌球蛋白 IIA (NM) 在 ATPase 中具有不同的温度依赖性。在我们检查的 II 类肌球蛋白（SK、SM 和 NM）中，ATP 酶测定中的限速步骤被认为是附着于肌动蛋白或磷酸盐释放，而对于体外运动测定而言，这是有争议的。在 MV 中，体外运动和 ATP 酶测定的限速步骤已知是 ADP 释放。因此，在 MV 中，ADP 释放速率常数的温度依赖性与体外运动的温度依赖性相似。有趣的是，SM 和 NM 的 ADP 释放速率常数的温度依赖性转向了体外运动温度依赖性。我们的结果表明，SK、SM 和 NM 中的限速步骤可能从溶液中的附着限制转变为体外运动测定中的分离限制。肌球蛋白分子内的内部应变或邻近肌球蛋白马达的内部应变可能会减慢 ADP 的释放，从而在体外运动测定中成为速率限制。在所检查的这一小部分肌球蛋白中，体外滑动速度与肌动蛋白激活的 ATP 酶活性具有相当好的相关性，Barany 的原始研究表明了这一点 (J Gen Physiol 50:197–218, 1967)。
We examined the temperature dependence of muscle and non-muscle myosin (heavy meromyosin, HMM) with in vitro motility and actin-activated ATPase assays. Our results indicate that myosin V (MV) has a temperature dependence that is similar in both ATPase and motility assays. We demonstrate that skeletal muscle myosin (SK), smooth muscle myosin (SM), and non-muscle myosin IIA (NM) have different temperature dependence in ATPase compared to in vitro motility assays. In the class II myosins we examined (SK, SM, and NM) the rate-limiting step in ATPase assays is thought to be attachment to actin or phosphate release, while for in vitro motility assays it is controversial. In MV the rate-limiting step for both in vitro motility and ATPase assays is known to be ADP release. Consequently, in MV the temperature dependence of the ADP release rate constant is similar to the temperature dependence of in vitro motility. Interestingly, the temperature dependence of the ADP release rate constant of SM and NM was shifted toward the in vitro motility temperature dependence. Our results suggest that the rate-limiting step in SK, SM, and NM may shift from attachment-limited in solution to detachment limited in the in vitro motility assay. Internal strain within the myosin molecule or by neighboring myosin motors may slow ADP release which becomes rate-limiting in the in vitro motility assay. Within this small subset of myosins examined, the in vitro sliding velocity correlates reasonably well with actin-activated ATPase activity, which was suggested by the original study by Barany (J Gen Physiol 50:197–218, 1967).