SRSF Protein Kinase 2 (SRPK2)

Pre-mRNA splicing is a critical step in the posttranscriptional regulation of gene expression. This process requires small nuclear ribonucleoprotein particles (snRNPs) and non-snRNP splicing factors, both of which are stored in nuclear 'speckles.' Non-snRNP factors containing an arginine/serine-rich (RS) domain, designated 'SR proteins', are phosphorylated, predominantly on serines within their RS domains. The predicted Srpk2 protein contains conserved serine/threonine kinase domains, a proline-rich domain, a basic region which may be a nuclear localization signal, and an acidic domain. The mouse Srpk2 protein is 58% and 32% identical to the human SRPK1 and yeast Dsk1 proteins, respectively. The authors demonstrated that Srpk2 phosphorylated ASF/SF2 in vitro.