Fig. 2.
The SF3b complex in splicing. The SF3b complex is first recruited into the U2 snRNP during snRNP maturation, then incorporated into the spliceosome, and binds to BS-A during the spliceosome assembly and activation stages (A to Bact). Once the spliceosome is catalytically activated (B*), SF3b is displaced from U2/BPS for catalysis to occur and subsequently becomes loosely associated with the spliceosome until the end of splicing [35–40]. Structures of spliceosomal A (PDB accession code: 6G90, [25]) and Bact (PDB accession code: 5Z56, [27]) complexes depicted in surface mode and colored in gray are also shown above respective cartoons with SF3b colored the same as in Fig. 1b