Background：This gene encodes subunit 3 of the splicing factor 3b protein 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.
