FIGURE 3.

The model for PRMT5 roles in regulation of spliceosome. pICln recruits Sm proteins into the PRMT5 complex for methylation, then the methylated Sm proteins are loaded onto snRNAs to form snRNPs; The formation of Sm D2/D1 dimers and their binding to pICln ensures their release and subsequent delivery to the PRMT5 complex; The loss of Sm protein SDMA prevents the recruitment of the NineTeen complex and the initiation of spliceosome activation; ZNF326 interacts with PRMT5 and WDR77, and HNRNPH1, the loss of PRMT5 and WDR77 leads to the overall defect of alternative splicing.