Avrova S V, Borovikov Y S, Efimova N N, Chacko S
Laboratory of Molecular Mechanisms of Cell Motility, Institute of Cytology, Russian Academy of Sciences, St.-Petersburg.
FEBS Lett. 1998 Jul 3;430(3):266-8. doi: 10.1016/s0014-5793(98)00675-9.
The effect of Ca2+ on conformational changes in rhodamine-phalloidin-labeled F-actin induced by binding of smooth muscle heavy meromyosin (HMM) with either phosphorylated or dephosphorylated regulatory light chains (LC20) was studied by polarized fluorimetry. LC20 phosphorylation caused alterations in the F-actin structure typical of the force-producing (strong-binding) state, while dephosphorylation of the chains led to alterations typical of the formation of non-force-producing (weak-binding) state of the actomyosin complex. The presence of Ca2+ enhanced the effect of LC20 phosphorylation and weakened the effect of LC20 dephosphorylation. These data suggest that Ca2+ modulates actin-myosin interaction in smooth muscle by promoting formation of the strong-binding state.
通过偏振荧光法研究了Ca2+对平滑肌重酶解肌球蛋白（HMM）与磷酸化或去磷酸化调节轻链（LC20）结合诱导的罗丹明-鬼笔环肽标记的F-肌动蛋白构象变化的影响。LC20磷酸化导致F-肌动蛋白结构发生变化，这是产生力的（强结合）状态的典型特征，而轻链去磷酸化则导致肌动球蛋白复合物形成非产生力的（弱结合）状态的典型变化。Ca2+的存在增强了LC20磷酸化的作用，并减弱了LC20去磷酸化的作用。这些数据表明，Ca2+通过促进强结合状态的形成来调节平滑肌中的肌动蛋白-肌球蛋白相互作用。
