BIOCHEMISTRY OF NEW MYOFIBRILLAR PROTEINS

我们建议继续我们的研究分子性质和 两个巨大的主要肌原纤维的肌节组织 蛋白质--肌联蛋白和星云蛋白--它们存在于骨骼和 广泛的脊椎动物和无脊椎动物物种的心肌。 我们在过去几年的研究表明，肌联蛋白和星云蛋白可能是 弹性连续肌丝的组成部分（“第三”丝）-- 与此不同的是肌节内的粗丝。 在 在下一个资助期内，我们建议（a）进一步研究 肌联蛋白和星云蛋白的性质，强调天然 蛋白质，结构域组织的研究，免疫学的研究 性质，形态的可视化及其研究 与其他肌原纤维蛋白的相互作用;（B）继续并扩展我们的 抗体定位研究，包括使用单克隆抗体 和电子显微镜技术，强调检测和标记 肌节中的肌丝;（c）表征 肌联蛋白和星云蛋白的磷酸化和钙结合性质， 强调这些蛋白质可能参与调节 （d）对这些机构的分布和组织情况进行调查 在自然界中的titin和nebulin，强调它们在昆虫飞行中的存在 在肌肉和非肌肉细胞中。 我们希望生物化学和结构 这里提出的研究将导致更好地了解结构 和收缩机制的功能， 横纹肌收缩和舒张的机制。

We propose to continue our studies on the molecular properties and the sarcomeric organization of two extremely large, major myofibrillar proteins\-- titin and nebulin -- which are found in the skeletal and cardiac muscles of a wide range of vertebrate and invertebrate species. Our studies in the past years have indicated that titin and nebulin may be components of an elastic, continuous myofilament (the "third" filament) -- distinct from this and thick filaments -- within the sarcomere. In the next grant period, we propose to (a) investigate further the molecular properties of titin and nebulin emphasizing the purification of native proteins, the study of domain organization, the study of immunological properties, the visualization of morphology and the investigation of their interactions with other myofibrillar proteins; (b) continue and extend our antibody localization studies to include the use of monoclonal antibodies and electron microscopic techniques, emphasizing the detection and labeling of ultrathin filaments in the sarcomere; (c) characterize the phosphorylation and calcium binding properties of titin and nebulin, emphasizing the possible involvement of these proteins in regulatory mechanisms; and (d) perform a survey of the distribution and organization of titin and nebulin in nature, emphasizing their presence in insect flight muscle and in nonmuscle cells. We hope that the biochemical and structural studies proposed here will lead to better understanding of the structure and function of contractile machinery, the mechanical properties of striated muscle and the mechanism of muscle contraction and relaxation.