Serine/Arginine Rich Splicing Factor 2B (SRSF2B)

The highly conserved SR family contains phosphoproteins that act as both essential and alternative splicing factors. By screening a genomic library with a fragment of the PR264, or SC35, gene (SFRS2), Soret et al. (1998) isolated clones of the SRp46 gene. Based on sequence and gene structure analyses, the authors concluded that SRp46 is likely a processed PR264 pseudogene. SRp46 is expressed in several human cell lines and tissues. While monkey cells express SRp46 sequences, mice do not have an SRp46 homolog. The predicted human SRp46 protein has 282 amino acids and a calculated molecular mass of 35 kD. However, SRp46 migrated as a 46-kD protein on Western blots of HeLa cell nuclear extracts; Soret et al. (1998) noted that SR proteins generally exhibit abnormal gel mobility, due mainly to extensive phosphorylation of serine residues.