• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Canadian Journal of Physiology and Pharmacology >Vectorial activation of smooth muscle myosin filaments and its modulation by telokin.
【24h】

Vectorial activation of smooth muscle myosin filaments and its modulation by telokin.

机译：平滑肌肌球蛋白丝的矢量激活及其由telokin的调节。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Smooth muscle myosin copurifies with myosin light chain kinase (MLCK) and calmodulin (CaM) as well as with variable amounts of myosin phosphatase. Therefore, myosin filaments formed in vitro also contain relatively high levels of these enzymes. Thus these filaments may be considered to be native-like because they are similar to those expected to exist in vivo. These endogenous enzymes are present at high concentrations relative to myosin, sufficient for rapid phosphorylation and dephosphorylation of the filaments at rates comparable to those observed for contraction and relaxation in intact muscle strips. The phosphorylation by MLCK/CaM complex appears to exhibit some directionality and is not governed by a random diffusional process. For the mixtures of myosin filaments with and without the endogenous MLCK/CaM complex, the complex preferentially phosphorylates its own parent filament at a higher rate than the neighboring filaments. This selective or vectorial-like activation is lost or absent when myosin filaments are dissolved at high ionic strength. Similar vectorial-like activation is exhibited by the reconstituted filament suspensions, but the soluble systems composed of isolated regulatory light chain or soluble myosin head subfragments exhibit normal diffusional kinetic behavior. At physiological concentrations, kinase related protein (telokin) effectively modulates the activation process by reducing the phosphorylation rate of the filaments without affecting the overall phosphorylation level. This results from telokin-induced liberation of the active MLCK/CaM complex from the filaments, so that the latter can also activate the neighboring filaments via a slower diffusional process. When this complex is bound at insufficient levels, this actually results in acceleration of the initial phosphorylation rates. In short, I suggest that in smooth muscle, telokin plays a chaperone role for myosin and its filaments.
机译：平滑肌肌球蛋白与肌球蛋白轻链激酶（MLCK）和钙调蛋白（CaM）以及可变数量的肌球蛋白磷酸酶共纯化。因此，体外形成的肌球蛋白丝也含有相对较高水平的这些酶。因此，这些细丝可以被认为是天然的，因为它们类似于预期存在于体内的细丝。这些内源酶以相对于肌球蛋白高的浓度存在，足以使细丝快速磷酸化和去磷酸化，其速率与在完整的肌肉条中观察到的收缩和松弛相当。 MLCK / CaM复合物的磷酸化似乎表现出一定的方向性，不受随机扩散过程的控制。对于具有和不具有内源性MLCK / CaM复合物的肌球蛋白细丝的混合物，该复合物优先以比相邻细丝更高的速率磷酸化其自身的母体细丝。当肌球蛋白丝以高离子强度溶解时，这种选择性的或矢量样的活化作用消失或消失。重构的细丝悬浮液表现出类似的矢量样活化，但由分离的调节性轻链或可溶性肌球蛋白头亚片段组成的可溶性系统表现出正常的扩散动力学行为。在生理浓度下，激酶相关蛋白（telokin）可通过降低细丝的磷酸化率来有效地调节激活过程，而不会影响总的磷酸化水平。这是由于telokin诱导活性MLCK / CaM复合物从细丝中释放出来的，因此后者也可以通过较慢的扩散过程激活相邻的细丝。当该络合物以不足的水平结合时，这实际上导致初始磷酸化速率的加速。简而言之，我建议在平滑肌中，telokin对肌球蛋白及其细丝起着伴侣的作用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号