SR proteins: a conserved family of pre-mRNA splicing factors.

TLDR

SR proteins are a conserved family of nuclear phosphoproteins recognized by a monoclonal antibody that binds to RNA polymerase II transcription sites. The study examines the potential role of SR proteins in pre‑mRNA splicing. The authors purified the SR protein family to homogeneity by two salt precipitations and characterized five members (20–75 kDa) with serine‑arginine‑rich C‑terminal domains. Four SR proteins from calf thymus restore splicing in a deficient extract with multiple pre‑mRNA substrates, and microsequencing shows they are related but distinct, with four containing a repeated RNA‑recognition motif.

Abstract

We demonstrate that four different proteins from calf thymus are able to restore splicing in the same splicing-deficient extract using several different pre-mRNA substrates. These proteins are members of a conserved family of proteins recognized by a monoclonal antibody that binds to active sites of RNA polymerase II transcription. We purified this family of nuclear phosphoproteins to apparent homogeneity by two salt precipitations. The family, called SR proteins for their serine- and arginine-rich carboxy-terminal domains, consists of at least five different proteins with molecular masses of 20, 30, 40, 55, and 75 kD. Microsequencing revealed that they are related but not identical. In four of the family members a repeated protein sequence that encompasses an RNA recognition motif was observed. We discuss the potential role of this highly conserved, functionally related set of proteins in pre-mRNA splicing.