Silver P J, Holroyde M J, Solaro R J, Disalvo J
Biochim Biophys Acta. 1981 Apr 17;674(1):65-70. doi: 10.1016/0304-4165(81)90347-0.
Incubation of bovine aortic native actomyosin with cyclic AMP and bovine aortic cyclic AMP-dependent protein kinase produced a rightward shift in the relation between free Ca2+ and both superprecipitation and actomyosin ATPase activity. The relation between free Ca2+ and phosphorylation of myosin light chains was also shifted to the right. The concentration of free Ca2+ required for half-maximal activation of both ATPase activity and myosin light chain phosphorylation was approximately 1.0 microM for control actomyosin and 2.5 microM for actomyosin incubated with cyclic AMP-protein kinase. Neither basal nor maximal activities were significantly affected by incubation with cyclic AMP-protein kinase. Addition of e microM calmodulin to cyclic AMP-protein kinase-treated actomyosin relieved inhibition of both superprecipitation and myosin light chain phosphorylation. These findings suggest that cyclic AMP-protein kinase-mediated inhibition of actin-myosin interactions in vascular smooth muscle involve a shift in the Ca2+ sensitivity of the system. This shift probably involves Ca2+-calmodulin interactions and the control of phosphorylation of the myosin light chains.
牛主动脉天然肌动球蛋白与环磷酸腺苷（cAMP）及牛主动脉环磷酸腺苷依赖性蛋白激酶一起温育，导致游离钙离子（Ca2+）与超沉淀以及肌动球蛋白ATP酶活性之间的关系向右移动。游离Ca2+与肌球蛋白轻链磷酸化之间的关系也向右移动。对于对照肌动球蛋白，ATP酶活性和肌球蛋白轻链磷酸化半最大激活所需的游离Ca2+浓度约为1.0微摩尔，而与环磷酸腺苷 - 蛋白激酶一起温育的肌动球蛋白则为2.5微摩尔。基础活性和最大活性均未因与环磷酸腺苷 - 蛋白激酶温育而受到显著影响。向经环磷酸腺苷 - 蛋白激酶处理的肌动球蛋白中添加1微摩尔钙调蛋白可缓解对超沉淀和肌球蛋白轻链磷酸化的抑制。这些发现表明，环磷酸腺苷 - 蛋白激酶介导的血管平滑肌中肌动蛋白 - 肌球蛋白相互作用的抑制涉及该系统Ca2+敏感性的改变。这种改变可能涉及Ca2+ - 钙调蛋白相互作用以及肌球蛋白轻链磷酸化的控制。
