Hemicentin assembly in the extracellular matrix is mediated by distinct structural modules
Hemicentin assembly in the extracellular matrix is mediated by distinct structural modules
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DOI：
10.1074/jbc.m513589200
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发表时间：
2006-08-18
影响因子：
4.8
通讯作者：
Vogel, Bruce E.
中科院分区：
文献类型：
--
作者：
Dong, Chun;Muriel, Joaquin M.;Vogel, Bruce E.
半胱氨酸蛋白是保守的细胞外基质蛋白，其特征在于在氨基末端的单个冯维勒布兰德A（VWA）结构域、串联免疫球蛋白结构域的长延伸（> 40）、多个串联表皮生长因子（EGF）和单个纤蛋白样羧基末端模块。在秀丽隐杆线虫中，半蛋白质从肌肉和性腺前导细胞分泌，并在多个位置组装成离散的轨道，将细胞接触的广泛区域收缩成粘性和柔性的线形接头。为了确定对功能和组装至关重要的半蛋白质结构域，我们在C.优美的我们发现，含有VWA结构域的半纤维素片段可以靶向多个组装位点时，表达的控制下，无论是内源性半纤维素调控序列或肌肉特异性unc-54启动子。含有EGF和纤蛋白样羧基末端模块的半纤维蛋白片段可以与野生型动物中现有的半纤维蛋白聚合物共组装，但在缺乏内源性半纤维蛋白的情况下没有可检测的功能。这些数据表明，VWA结构域是细胞结合结构域，其功能是将半纤维素靶向到组装位点，并且EGF/纤蛋白样羧基末端模块构成组装结构域，其在半纤维素组装过程中介导半纤维素单体之间的直接相互作用。
Hemicentins are conserved extracellular matrix proteins characterized by a single von Willebrand A (VWA) domain at the amino terminus, a long stretch (> 40) of tandem immunoglobulin domains, multiple tandem epidermal growth factors (EGFs), and a single fibulin-like carboxyl-terminal module. In Caenorhabditis elegans, hemicentin is secreted from muscle and gonadal leader cells and assembles at multiple locations into discrete tracks that constrict broad regions of cell contact into adhesive and flexible line-shaped junctions. To determine hemicentin domains critical for function and assembly, we have expressed fragments of hemicentin as GFP tagged fusion proteins in C. elegans. We find that a hemicentin fragment containing the VWA domain can target to multiple assembly sites when expressed under the control of either endogenous hemicentin regulatory sequences or the muscle-specific unc-54 promoter. A hemicentin fragment containing the EGF and fibulin-like carboxyl-terminal modules can co-assemble with existing hemicentin polymers in wild-type animals but has no detectable function in the absence of endogenous hemicentin. The data suggest that the VWA domain is a cell binding domain whose function is to target hemicentin to sites of assembly and the EGF/fibulin-like carboxyl-terminal modules constitute an assembly domain that mediates direct interactions between hemicentin monomers during the hemicentin assembly process.