Yamanoue Minoru, Ueda Shuji, Ohashi Akiko, Yoshimura Yumi, Norioka Shigemi
Faculty of Agriculture, Kobe University, Kobe, Hyogo 657-8501, Japan.
Biosci Biotechnol Biochem. 2003 Mar;67(3):563-9. doi: 10.1271/bbb.67.563.
In order to clarify the position where paratropomyosin binds to connectin in the A-I junction region of a sarcomere, chicken beta-connectin was digested by Staphylococcus aureus V8 protease under denaturing conditions and the digested peptides were electrophoretically separated. Five peptides, 150-kDa, 100-kDa, 70-kDa, and 43-kDa fragments, were simultaneously detected by biotinylated paratropomyosin and an anti-connectin monoclonal antibody. The N-terminal sequence of the 43-kDa fragment was found to be YQFRVYAVNK, similar to the sequence of 7556-7565 amino acids in the I51 fibronectin type 3 domain that was located at the A-I junction region of human cardiac titin/connectin. Therefore, we propose that paratropomyosin binds to the 43-kDa fragment from beta-connectin at the A-I junction region in both living muscle and in muscle immediately postmortem, and the N-terminus of the 43-kDa fragment is localized in the I51 domain.
为了阐明副肌球蛋白在肌节A-I连接区域与肌联蛋白结合的位置，在变性条件下用金黄色葡萄球菌V8蛋白酶消化鸡β-肌联蛋白，并对消化后的肽段进行电泳分离。通过生物素化的副肌球蛋白和抗肌联蛋白单克隆抗体同时检测到了5种肽段，即150-kDa、100-kDa、70-kDa和43-kDa片段。发现43-kDa片段的N端序列为YQFRVYAVNK，与位于人心肌肌联蛋白/A-I连接区域的I51纤连蛋白III型结构域中7556-7565位氨基酸序列相似。因此，我们提出在活体肌肉和刚死后的肌肉中，副肌球蛋白均在A-I连接区域与β-肌联蛋白的43-kDa片段结合，且43-kDa片段的N端位于I51结构域。
