SF3B1, SAP155, Splicing factor 3B subunit 1, Pre-mRNA-splicing factor SF3b 155 kDa subunit, SF3b155, Spliceosome-associated protein 155, SAP 155
SF3B1 is subunit 1 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 introns branch site in a sequence independent manner and may anchor the U2 snRNP to the pre-mRNA.