New proteins related to the Ser-Arg family of splicing factors

Benjamin J. Blencowe, Robbyn Issner, Jaesang Kim, Patrick Mccaw, Phillip A. Sharp

Research output: Contribution to journalArticlepeer-review

58 Scopus citations


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 He La 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-lariat 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.

Original languageEnglish
Pages (from-to)852-865
Number of pages14
Issue number8
StatePublished - 1995


  • Alternative splicing
  • Nuclear matrix antigens
  • Ser-Arg domain phosphorylation
  • Spliceosome


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