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NEW ELASTIC STRUCTURE OF GIANT SARCOMERE

巨型肌节的新弹性结构

基本信息

批准号：
10640661
负责人：
KIMURA Sumiko
金额：
$ 1.98万
依托单位：
CHIBA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640661/
关键词：
Crayfish claw Invertebrate Connectin Connectin-like Protein Giant sarcomere Elastic protein PEVK D-titin 無脊推動物

项目摘要

In vertebrate striated muscle, connectin (also called titin ) (MM 3000 kDa) extends from the Z line over the thick filament up to the M line of the sarcomere. One molecule spans a half sarcomere approximately 1.2μm long at rest. On the other hand, in giant sarcomeres of crayfish claw closer muscle the length of which is 8.3μm long at rest, a similar size of an elastic protein functions as connetin. How does the 3000 kDa protein cover such a long distance?The entire sequence of the 3000 kDa protein was predicted from the cDNA sequences cloned from crayfish claw closer cDNA library. Markedly different sequence from that of vertebrate connectin has been found. First of all, there are novel repeating motifs of 68 and 71 amino acid residues. Second, the number of immunogloblin C2 motif or fibronectin Type III, abundant in vertebrate connectin, is very small. Third, there are two large elastic PEVK domains, as compared to only one domain in vertebrate connectin. Fourth, the myosin light chain kinase domain common to connectin, projectin and twitchin is missing. Immunofluorescence microscopy using antibodies raised to three recombinant peptides demonstrated that the 68 residue repeats and a long spacer between the repeats and immunoglobulin domains were remarkably extensible when the sarcomere was stretched to a sarcomere length of 〜13μm. Furthermore, circular dichroism spectra suggested that a fusion protein of novel 68 repeat consists of 53% β-sheet and 22% β-turn.

在脊椎动物的横纹肌中，连接蛋白（也称为肌联蛋白）（MM 3000 kDa）从Z线延伸到肌节的粗丝上的M线。一个分子在静止时跨越约1.2μm长的半个肌节。另一方面，在小龙虾的巨大肌节中，休息时长度为8.3μm，类似大小的弹性蛋白质具有连接蛋白的功能。3000 kDa的蛋白质是如何覆盖如此长的距离的？从螯虾爪cDNA文库中克隆的cDNA序列预测了3000 kDa蛋白的全序列。首先，发现了与脊椎动物连接蛋白不同的68和71个氨基酸残基的重复序列。第二，在脊椎动物连接蛋白中丰富的免疫球蛋白C2基序或纤连蛋白III型的数量非常少。第三，有两个大的弹性PEVK结构域，相比之下，只有一个域在脊椎动物连接蛋白。第四，连接蛋白、投射蛋白和颤蛋白共有的肌球蛋白轻链激酶结构域缺失。使用针对三种重组肽的抗体的免疫荧光显微镜显示，当肌节被拉伸至约13μm时，68个残基的重复序列和重复序列与免疫球蛋白结构域之间的长间隔区显著可延伸。圆二色光谱分析表明，该融合蛋白由53%的β折叠和22%的β转角组成。