A novel function of myosin-binding protein-C

肌球蛋白结合蛋白-C(MyBP-C/C-Protein)是脊椎动物横纹肌中主要的肌球蛋白结合蛋白，由三种亚型组成。已证实MyBP-C在C端与LMM和Connectin/Titin相互作用，在N端与肌球蛋白的S2片段相互作用。已知MyBP-C与肌动蛋白细丝结合并调节肌球蛋白的肌动蛋白激活的ATPase。然而，MyBP-C的肌动蛋白结合区尚未完全阐明。在本研究中，我们在大肠杆菌表达系统中制备了心脏、快慢MyBP-C的N端重组片段。共沉淀实验表明，每个片段都与F-肌动蛋白结合。此外，MyBP-C的快速片段和心脏片段对肌动球蛋白ATPase活性有抑制作用。这提示MyBP-C在N末端肌肉收缩过程中调节肌动蛋白-肌球蛋白的相互作用。

Myosin-binding protein-C (MyBP-C/C-protein) is one of the major myosin-binding proteins in vertebrate striated muscles and consists of three isoforms. It has been demonstrated that MyBP-C interacts with LMM and connectin/titin at the C-terminus, and with the S2 segments of myosin at the N-terminus. It is also known that MyBP-C binds to actin filaments and modulates the actin-activated ATPase of myosin. However, actin-binding region of MyBP-C has not yet been fully clarified. In this study, we prepared recombinant N-terminal fragments of cardiac, fast and slow MyBP-C in an E.coli expression system. Co-sedimentation assay showed that each fragment bound to F-actin. In addition, the fast and the cardiac fragment of MyBP-C inhibited the actomyosin ATPase activity. It suggests that MyBP-C regulates actin-myosin interaction during muscle contraction at the N-terminal side.