Splicing factor 3B subunit 3 is a protein that in humans is encoded by the SF3B3gene.
This gene encodes subunit 3 of the splicing factor 3bprotein complex. Splicing factor 3b, together with splicing factor 3a and a 12S RNA unit, forms the U2 small nuclear ribonucleoproteins complex (U2 snRNP). The splicing factor 3b/3a complex binds pre-mRNA upstream of the intron's branch site in a sequence independent manner and may anchor the U2 snRNP to the pre-mRNA. Splicing factor 3b is also a component of the minor U12-type spliceosome. Subunit 3 has also been identified as a component of the STAGA (SPT3-TAF(II)31-GCN5L acetylase) transcription coactivator-HAT (histone acetyltransferase) complex, and the TFTC (TATA-binding-protein-free TAF(II)-containing complex). These complexes may function in chromatin modification, transcription, splicing, and DNA repair.
Cavusoglu N; Brand M; Tora L; Van Dorsselaer A (2003). "Novel subunits of the TATA binding protein free TAFII-containing transcription complex identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry following one-dimensional gel electrophoresis". Proteomics. 3 (2): 217–23. doi:10.1002/pmic.200390030. PMID12601814. S2CID6035986.