DNA-binding protein involved in cell cycle control. May act as a transcription activator. Plays a role in pre-mRNA splicing as core component of precatalytic, catalytic and postcatalytic spliceosomal complexes (PubMed:11991638, PubMed:20176811, PubMed:28076346, PubMed:28502770, PubMed:29301961, PubMed:29360106, PubMed:29361316, PubMed:30705154, PubMed:30728453). Component of the PRP19-CDC5L complex that forms an integral part of the spliceosome and is required for activating pre-mRNA splicing. The PRP19-CDC5L complex may also play a role in the response to DNA damage (DDR) (PubMed:20176811). As a component of the minor spliceosome, involved in the splicing of U12-type introns in pre-mRNAs (Probable).