BIOCHEMISTRY OF NEW MYOFIBRILLAR PROTEINS

我们建议继续我们对分子性质的研究和对 两个极大的主要肌原纤维的肌节组织 蛋白质--肌动蛋白和星云蛋白--它们存在于骨骼和 各种脊椎动物和无脊椎动物的心肌。 我们在过去几年的研究表明，肌动蛋白和星云蛋白可能是 弹性的、连续的肌丝(“第三”丝)的组成部分-- 与这个和粗丝不同--在肌节内。在 在下一个资助期，我们建议(A)进一步研究分子 肌动蛋白和星云蛋白的性质强调天然的提纯 蛋白质，结构域组织的研究，免疫学的研究 性质、形态可视化及其研究进展 与其他肌原纤维蛋白的相互作用；(B)继续并延长我们的 包括使用单抗的抗体定位研究 和电子显微镜技术，强调检测和标记 肌节中的超细细丝；(C)表征 肌动蛋白和雾化蛋白的磷酸化和钙结合特性， 强调这些蛋白质可能参与调控 机制；和(D)对分配和组织情况进行调查 自然界中的肌动蛋白和星云蛋白，强调它们在昆虫飞行中的存在 在肌肉和非肌肉细胞中。我们希望生化和结构 这里提出的研究将有助于更好地理解该结构 和收缩机械的功能，机械性能 横纹肌和肌肉收缩和放松的机制。

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.