Role of myosin-binding protein-C for muscle contraction

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之一，有心肌型、快骨骼型和慢骨骼型三种亚型，本研究制备了编码小鼠心肌型MyBP-C（C 0-C3）、快骨骼型MyBP-C（F1-F4）和慢骨骼型MyBP-C（S1-S4）的N端结构域。coli表达系统。我的研究结果表明，N-末端结构域的三个MyBP-C亚型交联（或捆绑）肌动蛋白丝和绑定到肌球蛋白丝。骨骼肌MyBP-C的N-末端也显著提高肌动蛋白激活的肌球蛋白ATP酶活性。此外，我还鉴定了原索动物MyBP-C在玻璃海鞘心肌中的表达。与脊椎动物MyBP-C一样，海鞘MyBP-C分别在N-末端和C-末端区域与肌动蛋白丝和肌球蛋白丝结合。

Myosin-binding protein-C (MyBP-C/ C-protein) is one of the major myosin binding proteins and has three isoforms (cardiac, fast-skeletal, slow-skeletal) in vertebrate striated muscles.In this study, I prepared N-terminal domains encoding mouse cardiac MyBP-C (C0 to C3), that of fast-skeletal MyBP-C (F1 to F4) and that of slow-skeletal MyBP-C (S1 to S4) in an E. coli expression system. My results showed that N-terminal domains of three MyBP-C isoforms cross-linked (or bundled) actin filaments and bound to myosin filaments. The N-terminus of fast skeletal MyBP-C also elevated actin-activated myosin ATPase activity significantly. Furthermore, I identified expression of protochordate MyBP-C in cardiac muscle of Ciona intestinalis. The ciona MyBP-C bound to actin filaments and myosin filaments at the N-terminal and C-terminal region, respectively, as well as vertebrate MyBP-C.