Kulikova N, Dabrowska R
Department of Muscle Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland.
Biochem Biophys Res Commun. 1996 Aug 5;225(1):195-202. doi: 10.1006/bbrc.1996.1153.
The influence of caldesmon on papain digestion of chicken gizzard monomeric myosin in folded (10S) conformation depends on its phosphorylation. Caldesmon exposes the head/rod junction of myosin in phosphorylated form to proteolytic attack (particularly in the presence of Ca2+) and slightly screens it in unphosphorylated form. In both folded forms RLCs are protected by caldesmon, more in unphosphorylated than in phosphorylated myosin. The results indicate that the conformations of folded unphosphorylated and phosphorylated myosin are distinct and suggest that caldesmon destabilizes the regulatory domain in folded conformation of phosphorylated myosin.
钙调蛋白对处于折叠（10S）构象的鸡胗单体肌球蛋白木瓜蛋白酶消化的影响取决于其磷酸化状态。磷酸化形式的钙调蛋白会使肌球蛋白的头部/杆部连接处暴露于蛋白水解攻击之下（尤其是在Ca2+存在的情况下），而未磷酸化形式则会对其稍有屏蔽作用。在两种折叠形式中，调节轻链（RLCs）均受到钙调蛋白的保护，在未磷酸化的肌球蛋白中受到的保护比磷酸化的肌球蛋白中更多。结果表明，折叠的未磷酸化和磷酸化肌球蛋白的构象是不同的，这表明钙调蛋白会使磷酸化肌球蛋白折叠构象中的调节结构域不稳定。
