Fig. 4
From: Structures of the human pre-catalytic spliceosome and its precursor spliceosome
Interactions between the SF3b complex and the U4/U6.U5 tri-snRNP. a Overall structural comparison between the human pre-B and B complexes. The two complexes are aligned on the basis of their respective U5 snRNA molecules. In the left panel, the human pre-B complex is color-coded whereas the entire B complex is shown grey. In the right panel, the B complex is color-coded and the pre-B complex is grey. The U6 LSm ring is translocated towards the tri-snRNP in the pre-B-to-B transition. The drastic relocation of Brr2 appears to trigger the translocation of the U4 Sm ring and its associated U4 snRNA sequences. b A close-up view on the interactions between the SF3b130 protein of the SF3b complex and the tri-snRNP. In the human pre-B complex (left panel), SF3b130 is close to the U4 Sm ring and its associated U4 snRNA elements. In the human B complex (right panel), SF3b130 directly interacts with the N-terminal α-helical domain of Smu1, whereas Brr2 binds the C-terminal WD40 domain of Smu1
