Wang C Y, Ngai P K, Walsh M P, Wang J H
Biochemistry. 1987 Feb 24;26(4):1110-7. doi: 10.1021/bi00378a019.
Fodrin, a spectrin-like actin and calmodulin binding protein, was purified to electrophoretic homogeneity from a membrane fraction of bovine brain. The effect of fodrin on smooth muscle actomyosin Mg2+-ATPase activity was examined by using a system reconstituted from skeletal muscle actin and smooth muscle myosin and regulatory proteins. The simulation of actomyosin Mg2+-ATPase by fodrin showed a biphasic dependence on fodrin concentration and on the time of actin and myosin preincubation at 30 degrees C. Maximal stimulation (50-70%) was obtained at 3 nM fodrin following 10 min of preincubation of actin and myosin. This stimulation was also dependent on the presence of tropomyosin. In the absence of myosin light chain kinase, the fodrin stimulation of Mg2+-ATPase could not be demonstrated with normal actomyosin but could be demonstrated with acto-thiophosphorylated myosin, suggesting that fodrin stimulation depends on the phosphorylation of myosin. Fodrin stimulation was shown to require the presence of both Ca2+ and calmodulin when acto-thiophosphorylated myosin was used. These observations suggest a possible functional role of fodrin in the regulation of smooth muscle contraction and demonstrate an effect on Ca2+ and calmodulin on fodrin function.
血影蛋白是一种类似于血影蛋白的肌动蛋白和钙调蛋白结合蛋白，从牛脑的膜组分中纯化至电泳纯。通过使用由骨骼肌肌动蛋白、平滑肌肌球蛋白和调节蛋白重构的系统，研究了血影蛋白对平滑肌肌动球蛋白Mg2 + -ATP酶活性的影响。血影蛋白对肌动球蛋白Mg2 + -ATP酶的模拟显示出对血影蛋白浓度以及肌动蛋白和肌球蛋白在30℃预孵育时间的双相依赖性。在肌动蛋白和肌球蛋白预孵育10分钟后，在3 nM血影蛋白时获得最大刺激（50 - 70%）。这种刺激也依赖于原肌球蛋白的存在。在没有肌球蛋白轻链激酶的情况下，用正常的肌动球蛋白无法证明血影蛋白对Mg2 + -ATP酶的刺激，但用肌动蛋白 - 硫代磷酸化肌球蛋白可以证明，这表明血影蛋白刺激依赖于肌球蛋白的磷酸化。当使用肌动蛋白 - 硫代磷酸化肌球蛋白时，血影蛋白刺激显示需要Ca2 +和钙调蛋白的存在。这些观察结果表明血影蛋白在平滑肌收缩调节中可能具有功能作用，并证明了Ca2 +和钙调蛋白对血影蛋白功能的影响。
