SR proteins: a foot on the exon before the transition from intron to exon definition.
Two recent publications illuminate the evolution of alternative splicing, showing that a SR (serine-arginine-rich) protein that regulates alternative splicing in multicellular organisms is also found in a unicellular organism without alternative splicing, in which it can assist in the splicing of weak introns. Moreover, insertion of SR proteins into an organism lacking such proteins can restore the splicing of weak introns. These results imply that SR proteins had already facilitated the splicing of weak introns before the evolution of alternative splicing.
Ram
Oren
O
Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel Aviv University, Ramat Aviv 69978, Israel.
Ast
Gil
G
D017398:Alternative Splicing / Q000235:genetics*; D019143:Evolution, Molecular; D007438:Introns / Q000235:genetics*; D008957:Models, Genetic; D009687:Nuclear Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D012568:Schizosaccharomyces / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics*; D000068103:Serine-Arginine Splicing Factors
D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; C120856:srP2 protein, S pombe; D000068103:Serine-Arginine Splicing Factors