Characterization of mammalian synemin, an intermediate filament protein present in all four classes of muscle cells and some neuroglial cells: co-localization and interaction with type III intermediate filament proteins and keratins
Characterization of mammalian synemin, an intermediate filament protein present in all four classes of muscle cells and some neuroglial cells: co-localization and interaction with type III intermediate filament proteins and keratins
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DOI：
10.1007/s00441-003-0732-2
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发表时间：
2003-01-01
影响因子：
3.6
通讯作者：
Ohara, O
中科院分区：
文献类型：
--
作者：
Hirako, Y;Yamakawa, H;Ohara, O
使用单克隆抗体，我们检测到高分子量的肌肉蛋白，与desmin共定位和共分离。通过对该蛋白部分氨基酸序列的人类cDNA数据库的检索，我们发现了一个编码1565个氨基酸的多肽的cDNA克隆，该克隆被鉴定为哺乳动物（人类）的synemin，是中间丝蛋白（IF）家族的成员。免疫印迹显示骨骼肌中存在180 kda的多肽，心脏和平滑肌中存在180和200 kda的多肽。有趣的是，在肌上皮细胞中也发现了突触蛋白，这些细胞有角蛋白丝而不是促球蛋白。此外，在视神经星形胶质细胞和非髓鞘形成的雪旺细胞中也发现了synemin，以及胶质纤维酸性蛋白（GFAP）和vimentin。印迹覆盖表明，赛门明与去丝蛋白、波形蛋白、GFAP和角蛋白5和6存在分子相互作用，但与角蛋白14没有相互作用。实验数据还表明，这可能与一种骨骼肌蛋白星云蛋白有关。纯化的赛门明以不同的摩尔比与聚丝蛋白共同组装，在1:25的比例下，形成了与聚丝蛋白长度相当的纤维。然而，当摩尔比为3:25和6:25时，生成的丝状聚合物更短且形状不规则。赛门明存在于所有四类肌肉细胞和一种特定类型的神经胶质细胞中，这一事实表明它具有重要的功能。它的结合可能使中频细胞骨架具有结构和功能上的通用性。
Using a monoclonal antibody, we have detected a high molecular weight muscle protein, co-localized and co-isolating with desmin. Searching a human cDNA database with partial amino acid sequences of the protein, we found a cDNA clone encoding a 1565-amino-acid polypeptide, identified as a mammalian (human) synemin, a member of the intermediate filament (IF) protein family. Immunoblotting showed the presence of a 180-kDa polypeptide in skeletal muscle and 180- and 200-kDa polypeptides in cardiac and smooth muscles. Interestingly, synemin was also found in myoepithelial cells, which have keratin filaments instead of desmin. Moreover, synemin was also found in astrocytes of optic nerves and non-myelin-forming Schwann cells, together with glial fibrillary acidic protein (GFAP) and vimentin. Blot overlays pointed to molecular interactions of synemin with desmin, vimentin, GFAP and keratin 5 and 6, but not with keratin 14. The experimental data also suggested a possible link with nebulin, a skeletal muscle protein. Purified synemin was coassembled with desmin in different molar ratios, and at 1:25, as typically found in vivo, IFs were formed which were comparable in length to desmin filaments. However, at molar ratios of 3:25 and 6:25, much shorter and irregular shaped filamentous polymers were generated. The fact that synemin is present in all four classes of muscle cells and a specific type of glial cells is indicative of important functions. Its incorporation may give structural and functional versatility to the IF cytoskeleton.