Mouse Monoclonal Antibody to SF3B4
Cat# MCA-3A1

      Splicing factor SF3B4, also known as SAP49, is a ubiquitously expressed protein found in the nuclei of eukaryotic cells (1). The protein is also known as splicing factor 3b, subunit 4, 49kDa SAP49, spliceosome-associated protein U2, Hsh49 and MGC108282. SF3B4 is one of four protein components of the U2 small nuclear ribonucleoprotein (snRNP) dependent splicing factor protein complex, the others three being SAP130, SAP145 and SAP155 (2). SF3B4 is one of the numerous proteins to contain one or more RNA recognition motifs. These are ~70 amino acids domains which bind single stranded RNA, and the SF3B4 protein has two of these. The function of the U2 snRNP dependent spliceosome complex is to regulate mRNA splicing. A rare human genetic disorder, Nager syndrome, is caused by haploinsufficiency of SF3B4 (3,4). The syndrome is variable in effect in different individuals but is classified as one of the acrofacial dysostoses which affect the face and limbs. Another study shows that Rodriguez acrofacial dysostosis may also be caused by point mutations in the SF3B4 gene (5). Recent studies suggest that upregulation of SF3B4 expression is an early stage biomarker of hepatocellular carcinoma (HCC), the most common form of cancer of the liver (6). Interestingly, knock down of SF3B4 expression may be beneficial therapeutically to HCC and other cancer patients as reduced levels of this protein inhibit alternate splicing of mRNA as activation of mRNA splicing is a feature of many cancer cells (6).
      The MCA-3A1 antibody was made against full length recombinant human SF3B4 made in and purified from E. coli. Antibodies to this protein such as MCA-3A1 are excellent markers of nuclei and can be used to monitor the nuclear fraction in biochemical experiments. Since the protein is expressed in quite large amounts and ubiquitously in cells and tissues this antibody may also be used as western blotting standard. Mouse select image at left for larger view.