Studies on molecular structure of C-protein and its role in myofibrillogensis

C蛋白是一种主要的肌球蛋白结合蛋白，在肌原纤维形成过程中参与肌球蛋白组装和肌节中粗丝的登记。不同的C-蛋白亚型，快（F），慢（S），和心脏（C），存在于鸡和哺乳动物，和C-亚型是已知的第一次表达在鸡肌肉发育。本研究旨在阐明鸡心肌C蛋白的分子结构及其在肌原纤维形成中的作用，主要研究结果如下：1）获得了鸡心肌C蛋白的cDNA全序列及其推导的氨基酸序列。7个IgC 2结构域，3个纤连蛋白III型结构域和一个磷酸化位点被指定的分子和C-末端IgC 2被指定为肌球蛋白结合所必需的。此外，检测到C亚型的两种变体，其差异仅在于磷酸化位点的存在或不存在。两者都是通过发育过程在心肌中检测到的 ...更多信息 2）为了阐明C蛋白亚型的表达模式及其在哺乳动物肌肉发育中的作用，克隆了编码小鼠骨骼肌（F和S）C蛋白的cDNA，并测定了其全序列。在成年小鼠组织中，通过北方印迹在组织特异性fasion中检测到C-、F-、S-亚型的信息;然而，有趣的是，在已被归类为典型快肌的趾长伸肌（extensor digitalum longus）肌肉中可检测到F-和S-亚型。虽然已知C-亚型在鸡骨骼肌发育过程中首先瞬时表达，但在小鼠骨骼肌发育阶段中完全未检测到C-亚型，但S-亚型首先可检测到，随后出现F-亚型。基本上相同的结果，获得了在蛋白质水平上通过蛋白质印迹和间接免疫荧光方法与同种型特异性抗体。少

C-protein is a major myosin-binding protein involved in myosin assembly and registration of thick filaments in the sarcomeres during myofibrillogenesis. Distinct C-protein isoforms, fast (F), slow (S), and cardiac (C), are present in both chicken and mammals, and C-isoform is known to be first expressed during chicken muscle development. The present studies were carried out aiming to clarify the molecular structure of C-protein and its role in myofibrillogensis, and the following results were obtained.1) The complete cDNA sequence encoding chicken cardiac (C) C-protein and the deduced amino acid sequence were determined. Seven IgC2 domains, 3 fibronectin type III domains and a phosphorylation site were specified in the molecule and the C-terminal IgC2 was designated to be essential for myosin-binding. In addition, two variants of C isoform which differ only in the presence or absence of the phosphorylation site were detected. Both were detected in cardiac muscle through developmental s … More tages, while only the latter was in embryonic skeletal muscle.2) In order to clarify expression pattern of C-protein isoforms and their roles in mammalian muscle development, the cDNAs encoding mouse skeletal muscle (F and S) C-protein were cloned and determined the entire sequences. In adult mouse tissues, the messages for C-, F-, S- isoforms were detected in a tissue-specific fasion by Northern blotting ; interestingly, however, both F- and S-isoforms were detectable in EDL (extensor digitorum longus) muscle which has been categorized as a typical fast muscle. Although C-isoform is known to be expressed first and transiently during development of chicken skeletal muscles, C-isoform was not detected at all in mouse skeletal muscle through developmental stages, but S-isoform became detectable first, followed by appearance of F-isoform. Basically the same results were obtained at a protein level by means of Western blot and indirect immunofluorescence methods with isoform-specific antibodies. Less