Spliceosome subunit SF3b complex (SF3b complex)

The **Spliceosome subunit SF3b complex** is a highly conserved, multi-protein complex that forms a pivotal part of the U2 small nuclear ribonucleoprotein (snRNP) within the spliceosome[1][3][4][5]. Its primary role is the recognition and binding of the branch point sequence (especially the branch point adenosine) in precursor messenger RNA (pre-mRNA), facilitating the accurate assembly and activation of the spliceosome during the splicing process[1][4]. Structurally, the complex consists of several subunits (including SF3B1, SF3B2, SF3B3, SF3B4, SF3B5, SF3B6, and PHF5A) with SF3B1 functioning as the central scaffold for protein-protein and protein-RNA interactions[3]. Beyond its central role in splicing, the SF3b complex participates in mRNA 3’-end processing, export, and acts as a transcription coactivator in some contexts[2]. Dysregulation and mutations (notably in SF3B1) are frequently observed in several cancers and are being explored as both biomarkers and drug targets; multiple natural and synthetic compounds (e.g., pladienolide B, spliceostatin A, herboxidiene, E7107) exert antitumor effects by inhibiting SF3b function[4]. However, targeting this complex is associated with considerable safety concerns due to its essential function in general mRNA splicing[4].

Other names

Splicing factor 3B complexSF3B complexSpliceosomal factor 3B

Splicing inhibition by targeting the SF3B1–PHF5A subunits and disrupting branch point adenosine recognition, inhibiting spliceosome assembly