Carmichael J D, Winder S J, Walsh M P, Kargacin G J
Department of Physiology, University of Massachusetts Medical School, Worcester 01655, USA.
Can J Physiol Pharmacol. 1994 Nov;72(11):1415-9. doi: 10.1139/y94-204.
Calponin has been implicated in the regulation of smooth muscle contraction as a result of its ability to inhibit the actin-activated Mg ATPase of smooth muscle myosin. This inhibitory effect is abolished by phosphorylation of calponin by Ca2+/calmodulin-dependent protein kinase II or protein kinase C, and restored following dephosphorylation by a type 2A protein phosphatase. Confocal immunofluorescent images of isolated smooth muscle cells colabeled with antibodies to calponin and actin or to calponin and tropomyosin indicate that calponin is present on thin filaments throughout the cell cytoplasm. Both calponin phosphorylation and myosin light chain phosphorylation increased in intact smooth muscle tissue strips when they contracted in response to carbachol or the phosphatase inhibitor okadaic acid. These results support the hypothesis that calponin phosphorylation-dephosphorylation plays a role in regulating smooth muscle contraction.
钙调蛋白因其能够抑制平滑肌肌球蛋白的肌动蛋白激活的Mg ATP酶而参与平滑肌收缩的调节。钙调蛋白被Ca2+/钙调蛋白依赖性蛋白激酶II或蛋白激酶C磷酸化后，这种抑制作用就会被消除，而在被2A类蛋白磷酸酶去磷酸化后又会恢复。用钙调蛋白和肌动蛋白抗体或钙调蛋白和原肌球蛋白抗体共同标记的分离平滑肌细胞的共聚焦免疫荧光图像表明，钙调蛋白存在于整个细胞质中的细肌丝上。当完整的平滑肌组织条对卡巴胆碱或磷酸酶抑制剂冈田酸作出收缩反应时，钙调蛋白磷酸化和肌球蛋白轻链磷酸化都会增加。这些结果支持了钙调蛋白磷酸化-去磷酸化在调节平滑肌收缩中起作用的假说。
