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Structure and function of connectin, muscle elastic protein

连接素、肌肉弹性蛋白的结构与功能

基本信息

批准号：
60480018
负责人：
MARUYAMA Koscak
金额：
$ 4.48万
依托单位：
Chiba University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60480018/
关键词：
connectin elastic filament striated muscle サルコメア滑り説 β-シート

项目摘要

Connectin is a very long filamentous protein present in vertebrate striated myofibrils linking myosin filaments to neighboring Z lines in a sarcomere. This is the third filament in addition to myosin and actin filaments in muscle.In the present study, circular dichroism spectra suggested that connectin consists of 70 % beta sheet structure and 30 % random coil. Artifially made connectin fibers showed X ray diffraction corrresponding to beta sheet structure as seen in silk fiboin. The fibers could be reversibly stretched up to 30 % of the initial length with tention generation. Temperature dependence of tention generation suggested that the elasticity was not a simple entropy elasticity. Further work is required for the detailed elastic structure of the connectin filaments.It was observed that short actin filaments dispersed by sonication in the presence of beta-actinin formed a network by the addition of connectin. Binding of connectin to actin meshwork was studied by cosedimentation experiments. Tropomyosin did not interfere with the binding. However, Sl, myosin heads inhibited it. Thus when Sl was added to connectin-actin network, actin filaments decorated with Sl gradually released from the aggregate. Connectin evidently does not interfere with the actin myosin interaction, driving force for sliding.From the present study, it is proposed that connectin filaments loosely bound to actin filaments in the I band region and acts as a guideline when sliding of the actin filaments occurs. Connectin filaments bind to the myosin filaments but it is regarded that myosin and actin interactions are not hindered by connectin at all.

连接蛋白是存在于脊椎动物横纹肌原纤维中的非常长的丝状蛋白，其将肌球蛋白丝连接到肌节中的相邻Z线。圆二色光谱表明，连接蛋白由70%的β折叠结构和30%的无规卷曲结构组成。人工制造的连接蛋白纤维显示出与丝纤维蛋白中所见的β折叠结构相对应的X射线衍射。纤维可以可逆地拉伸到初始长度的30%，并产生张力。张力产生的温度依赖性表明，弹性不是简单的熵弹性。需要进一步研究连接蛋白细丝的详细弹性结构。观察到，在β-辅肌动蛋白存在下，通过超声分散的短肌动蛋白细丝通过添加连接蛋白形成了网络。通过共沉淀实验研究了连接蛋白与肌动蛋白网络的结合。原肌球蛋白不干扰结合。当连接素-肌动蛋白网络中加入S1时，被S1修饰的肌动蛋白丝逐渐从聚集体中释放出来。连接蛋白显然不干扰肌动蛋白肌球蛋白的相互作用，驱动力sliding.From目前的研究，它提出，连接蛋白丝松散绑定到肌动蛋白丝的I带区域，并作为一个指导方针时，滑动的肌动蛋白丝发生。连接蛋白丝与肌球蛋白丝结合，但认为肌球蛋白和肌动蛋白的相互作用根本不受连接蛋白的阻碍。