功能
function:Subunit of the splicing factor SF3B required for 'A' complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence (BPS) in pre-mRNA. Sequence independent binding of SF3A/SF3B complex upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA. May also be involved in the assembly of the 'E' complex. Belongs also to the minor U12-dependent spliceosome, which is involved in the splicing of rare class of nuclear pre-mRNA intron.,PTM:Phosphorylated. Phosphorylation occurs concomitantly with the splicing catalytic steps. Phosphorylation on Thr-244, Thr-248 and Thr-313 by cyclin-dependent kinases promotes interaction with PPP1R8 during mitosis.,similarity:Belongs to the SF3B1 family.,similarity:Contains 11 HEAT repeats.,subcellular location:During mitosis, transiently dispersed from the nuclear speckles to the cytoplasm.,subunit:Identified in the spliceosome C complex, at least composed of AQR, ASCC3L1, C19orf29, CDC40, CDC5L, CRNKL1, DDX23, DDX41, DDX48, DDX5, DGCR14, DHX35, DHX38, DHX8, EFTUD2, FRG1, GPATC1, HNRPA1, HNRPA2B1, HNRPA3, HNRPC, HNRPF, HNRPH1, HNRPK, HNRPM, HNRPR, HNRPU, KIAA1160, KIAA1604, LSM2, LSM3, MAGOH, MORG1, PABPC1, PLRG1, PNN, PPIE, PPIL1, PPIL3, PPWD1, PRPF19, PRPF4B, PRPF6, PRPF8, RALY, RBM22, RBM8A, RBMX, SART1, SF3A1, SF3A2, SF3A3, SF3B1, SF3B2, SF3B3, SFRS1, SKIV2L2, SNRPA1, SNRPB, SNRPB2, SNRPD1, SNRPD2, SNRPD3, SNRPE, SNRPF, SNRPG, SNW1, SRRM1, SRRM2, SYF2, SYNCRIP, TFIP11, THOC4, U2AF1, WDR57, XAB2 and ZCCHC8. Component of splicing factor SF3B which is composed of at least eight subunits; SF3B1/SAP155/SF3B155, SF3B2/SAP145/SF3B155, SF3B3/SAP130/SF3B130, SF3B4/SAP49/SF3B49, SF3B14A, PHF5A/SF3B14B, SF3B10 and SF3B125.Component of the B-WICH complex, at least composed of SMARCA5/SNF2H, BAZ1B/WSTF, SF3B1, DEK, MYO1C, ERCC6, MYBBP1A and DDX21. SF3B associates with the splicing factor SF3A and a 12S RNA unit to form the U2 small nuclear ribonucleoproteins complex (U2 snRNP). SF3B1 interacts directly with the splicing factor U2AF. Phosphorylated form interacts with PPP1R8.,