Splicing factor 3B subunit 4 (Pre-mRNA-splicing factor SF3b 49 kDa subunit) (Spliceosome-associated protein 49) (SAP 49)
1_MAAGP 6_ ISERN 11_ QDATV 16_ YVGGL 21_ DEKVS 26_ EPLLW 31_ ELFLQ 36_ AGPVV 41_ NTHMP 46_ KDRVT 51_ GQHQG 56_ YGFVE 61_ FLSEE 66_ DADYA 71_ IKIMN 76_ MIKLY 81_ GKPIR 86_ VNKAS 91_ AHNKN 96_ LDVGA 101_ NIFIG 106_ NLDPE 111_ IDEKL 116_ LYDTF 121_ SAFGV 126_ ILQTP 131_ KIMRD 136_ PDTGN 141_ SKGYA 146_ FINFA 151_ SFDAS 156_ DAAIE 161_ AMNGQ 166_ YLCNR 171_ PITVS 176_ YAFKK 181_ DSKGE 186_ RHGSA 191_ AERLL 196_ AAQNP 201_ LSQAD 206_ RPHQL 211_ FADAP 216_ PPPSA 221_ PNPVV 226_ SSLGS 231_ GLPPP 236_ GMPPP 241_ GSFPP 246_ PVPPP 251_ GALPP 256_ GIPPA 261_ MPPPP 266_ MPPGA 271_ AGHGP 276_ PSAGT 281_ PGAGH 286_ PGHGH 291_ SHPHP 296_ FPPGG 301_ MPHPG 306_ MSQMQ 311_ LAHHG 316_ PHGLG 321_ HPHAG 326_ PPGSG 331_ GQPPP 336_ RPPPG 341_ MPHPG 346_ PPPMG 351_ MPPRG 356_ PPFGS 361_ PMGHP 366_ GPMPP 371_ HGMRG 376_ PPPLM 381_ PPHGY 386_ TGPPR 391_ PPPYG 396_ YQRGP 401_ LPPPR 406_ PTPRP 411_ PVPPR 416_GPLRG
1: Component of the 17S U2 SnRNP complex of the spliceosome, a large ribonucleoprotein complex that removes introns from transcribed pre-mRNAs (PubMed:10882114, PubMed:12234937, PubMed:27720643, PubMed:32494006). The 17S U2 SnRNP complex (1) directly participates in early spliceosome assembly and (2) mediates recognition of the intron branch site during pre-mRNA splicing by promoting the selection of the pre-mRNA branch-site adenosine, the nucleophile for the first step of splicing (PubMed:12234937, PubMed:32494006). Within the 17S U2 SnRNP complex, SF3B4 is part of the SF3B subcomplex, which is required for 'A' complex assembly formed by the stable binding of U2 snRNP to the branchpoint sequence in pre-mRNA (PubMed:12234937, PubMed:27720643). Sequence independent binding of SF3A and SF3B subcomplexes upstream of the branch site is essential, it may anchor U2 snRNP to the pre-mRNA (PubMed:12234937). May also be involved in the assembly of the 'E' complex (PubMed:10882114). Also acts as a component of the minor spliceosome, which is involved in the splicing of U12-type introns in pre-mRNAs (PubMed:15146077, PubMed:33509932)