Synemin may function to directly link muscle cell intermediate filaments to both myofibrillar Z-lines and costameres
Synemin may function to directly link muscle cell intermediate filaments to both myofibrillar Z-lines and costameres
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DOI：
10.1074/jbc.m104005200
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发表时间：
2001-08-24
影响因子：
4.8
通讯作者：
Robson, RM
中科院分区：
文献类型：
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作者：
Bellin, RM;Huiatt, TW;Robson, RM
Synemin 是一种大型中间丝 (IF) 蛋白，已在所有类型的肌肉细胞中鉴定出与含有结蛋白和/或波形蛋白的 IF 相关。我们之前的研究（Bellin, R. M., Sernett, S. W., Becker, B., Ip, W., Huiatt, T. W., and Robson, R. M. (1999) J. Biol. Chem. 274, 29493-29499）证明，synemin 与主要 IF 蛋白形成杂聚 IF，并含有肌原纤维 Z 线蛋白的结合位点α-肌动蛋白。通过利用印迹重叠测定，我们在此表明，synemin 也与肋节蛋白纽蛋白相互作用。此外，利用Gal4酵母双杂交系统的广泛测定证明了synemin与结蛋白和波形蛋白的相互作用，并且另外更精确地定义了synemin/α-肌动蛋白和synemin/纽蛋白相互作用离子中涉及的蛋白质子结构域。类似于 Synemin 的 300 个氨基酸区域的 C 端结合到 α-肌动蛋白的 N 端头和中心杆结构域以及类似于纽蛋白的 150 个氨基酸的 C 端尾部。总体而言，这些相互作用表明 Synemin 可能通过与 α-辅肌动蛋白的相互作用将 IF 锚定到肌原纤维 Z 线上，并通过与纽蛋白和/或 α-辅肌动蛋白的相互作用将 IF 锚定到肌膜处的肋节。这些连接将使 IF 能够直接连接所有细胞肌原纤维并将肌原纤维的外周层锚定到肋骨。
Synemin is a large intermediate filament (IF) protein that has been identified in all types of muscle cells in association with desmin- and/or vimentin-containing IFs. Our previous studies (Bellin, R. M., Sernett, S. W., Becker, B., Ip, W., Huiatt, T. W., and Robson, R. M. (1999) J. Biol. Chem. 274, 29493-29499) demonstrated that synemin forms heteropolymeric IFs with major IF proteins and contains a binding site for the myofibrillar Z-line protein alpha -actinin. By utilizing blot overlay assays, we show herein that synemin also interacts with the costameric protein vinculin. Furthermore, extensive assays utilizing the Gal4 yeast two-hybrid system demonstrate interactions of synemin with desmin and vimentin and additionally define more precisely the protein subdomains involved in the synemin/alpha -actinin and synemin/vinculin interact-ions. The C-terminal similar to 300-amino acid region of synemin binds to the N-terminal head and central rod domains of alpha -actinin and the similar to 150-amino acid C-terminal tail of vinculin. Overall, these interactions indicate that synemin may anchor IFs to myofibrillar Z-lines via interactions with alpha -actinin and to costameres at the sarcolemma via interactions with vinculin and/or alpha -actinin. These linkages would enable the IFs to directly link all cellular myofibrils and to anchor the peripheral layer of myofibrils to the costameres.