Blencowe B J, Issner R, Kim J, Mccaw P, Sharp P A
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139, USA.
RNA. 1995 Oct;1(8):852-65.
A family of six highly conserved proteins that contain domains rich in alternating serine/arginine residues (SR proteins) function in the regulation of splice site selection and are required for splicing. Using a selective precipitation method, more than 35 proteins were detected in nuclear extracts of HeLa cells that co-fractionate with the defined SR family. Many of these proteins were recognized by three monoclonal antibodies that bind to distinct phosphoepitopes on SR proteins. Two of these SR-related proteins were identified as the nuclear matrix antigens B1C8 and B4A11, which previously have been implicated in splicing. A subset of SR proteins, in their phosphorylated state, are associated with spliceosome complexes through both steps of the splicing reaction, remaining preferentially bound to complexes containing the exon-product. In contrast, other SR-related proteins appear to remain specifically associated with the intron-Iariat complex. The results indicate the existence of a potentially large group of SR-related proteins, and also suggest possible additional functions of SR proteins at a post-splicing level.
一个由六种高度保守的蛋白质组成的家族，其含有富含交替丝氨酸/精氨酸残基的结构域（SR蛋白），在剪接位点选择的调控中发挥作用，并且是剪接所必需的。使用一种选择性沉淀方法，在HeLa细胞核提取物中检测到35种以上与已定义的SR家族共分级分离的蛋白质。这些蛋白质中的许多被三种单克隆抗体识别，这些抗体与SR蛋白上不同的磷酸化表位结合。其中两种与SR相关的蛋白质被鉴定为核基质抗原B1C8和B4A11，它们先前已被认为与剪接有关。一部分SR蛋白在其磷酸化状态下，在剪接反应的两个步骤中都与剪接体复合物相关联，优先保留与包含外显子产物的复合物结合。相反，其他与SR相关的蛋白质似乎仍然特异性地与内含子套索复合物相关联。结果表明存在潜在的大量与SR相关的蛋白质，并且还暗示了SR蛋白在剪接后水平上可能的其他功能。
