Serine/Arginine Rich Splicing Factor 5 (SRSF5)

SFRS5is 259 amino acids long and is highly basic. The sequence of HRS is related to the human SF2/ASF protein and the Drosophila B52/SRp55 protein. The latter has been shown to function in vitro to regulate 5-prime splice site selection. Northern blots showed highest levels of HRS transcription in the spleen and thymus, tissues with actively proliferating cells. The authors noted that HRS is likely to be a member of a larger family of regulators of alternative pre-mRNA splicing.

Human SRp40 is 99% similar at the amino acid level and 94% similar at the nucleotide level within the coding sequence to rat HRS. Recombinant SRp40 protein is active in constitutive splicing, as shown by its ability to complement a HeLa cell S100 extract deficient in SR proteins.