Co-evolution of the branch site and SR proteins in eukaryotes

Abstract

Serine-arginine-rich (SR) proteins are essential for splicing in metazoans but are absent in yeast. By contrast, many fungi have SIR protein homologs with variable arginine-rich regions analogous to the arginine-serine-rich (RS) domain in metazoans. The density of RS repeats in these regions correlates with the conservation of the branch site signal, providing evidence for an ancestral origin of SR proteins and indicating that the SIR proteins and the branch site co-evolved. Show more