Goldberg A F, Moritz O L, Molday R S
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
Biochemistry. 1995 Oct 31;34(43):14213-9. doi: 10.1021/bi00043a028.
Peripherin/rds is a 39 kDa integral membrane glycoprotein essential for normal photoreceptor cell development in vertebrates. It has been implicated in several human retinal degenerative diseases including retinitis pigmentosa and macular degeneration and is thought to play a structural role at photoreceptor outer segment disk rims, where it forms a tightly-associated complex with rom-1, a nonglycosylated 37 kDa homologue. Western blot analysis of COS-1 cells transiently transfected with full-length cDNA coding for either peripherin/rds or rom-1 indicates that each protein is expressed primarily as a disulfide-linked homodimer; recombinant peripherin/rds is glycosylated while recombinant rom-1 is not--akin to their counterparts in rod photoreceptor disk membranes. Upon cotransfection of the two cDNAs, the specific assembly of a stable peripherin/rds--rom-1 complex is observed. Immunofluorescence microscopy studies demonstrate that both singly and coexpressed peripherin/rds and rom-1 complexes are localized primarily within internal membranes of transfected cells. Velocity sedimentation data indicate that the recombinant complexes (4.9 S) are assembled with a subunit stoichiometry similar to those extracted from ROS membranes (4.5 S) and are most consistent with a tetrameric arrangement of polypeptides. Sedimentation analyses of individually expressed peripherin/rds (5.1 S) and rom-1 (4.3 S) suggest that each polypeptide can also assemble into a tetrameric form in the absence of its homologue partner. Subunit assembly and interactions are discussed in terms of their potential role in hereditary retinal diseases.
外周蛋白/视网膜变性慢病毒（Peripherin/rds）是一种39 kDa的整合膜糖蛋白，对脊椎动物正常光感受器细胞的发育至关重要。它与多种人类视网膜退行性疾病有关，包括色素性视网膜炎和黄斑变性，并且被认为在光感受器外段盘缘发挥结构作用，在那里它与rom-1形成紧密相关的复合物，rom-1是一种非糖基化的37 kDa同源物。对瞬时转染了编码外周蛋白/视网膜变性慢病毒或rom-1的全长cDNA的COS-1细胞进行的蛋白质印迹分析表明，每种蛋白质主要以二硫键连接的同型二聚体形式表达；重组外周蛋白/视网膜变性慢病毒是糖基化的，而重组rom-1不是——这与它们在视杆光感受器盘膜中的对应物相似。当共转染这两种cDNA时，可观察到稳定的外周蛋白/视网膜变性慢病毒-rom-1复合物的特异性组装。免疫荧光显微镜研究表明，单独表达和共表达的外周蛋白/视网膜变性慢病毒和rom-1复合物主要定位于转染细胞的内膜内。速度沉降数据表明，重组复合物（4.9 S）的组装亚基化学计量与从视杆外段膜中提取的复合物（4.5 S）相似，并且最符合多肽的四聚体排列。对单独表达的外周蛋白/视网膜变性慢病毒（5.1 S）和rom-1（4.3 S）的沉降分析表明，在没有同源伴侣的情况下，每种多肽也可以组装成四聚体形式。根据它们在遗传性视网膜疾病中的潜在作用讨论了亚基组装和相互作用。
