Splicing factor SF3B4

Splicing factor SF3B4, also known as SAP49, is a ubiquitously expressed splicing factor found in the nuclei of eukaryotic cells, although it migrates into the cytoplasm of dividing cells. It was originally identified by as the protein most efficiently UV cross-linked to the A, B and C spliceosomal complexes.

The protein contains two of the highly conserved RRM type RNA recognition motifs, each corresponding to a small ~70 amino acid structure, consisting of 4 beta strands and two alpha-helices. Proteins containing these proteins are believed to have a role in the regulation of mRNA splicing. The protein runs on SDS-PAGE gels at an apparent molecular weight of 49kDa. This protein is known as splicing factor 3b, subunit 4, 49kDa SAP49, spliceosome-associated protein (U2 snRNP), Hsh49 and MGC108282. Antibodies to this protein are good markers of nuclei.