Involved in pre-mRNA splicing as component of the U4/U6-U5 tri-snRNP complex, one of the building blocks of the spliceosome (PubMed:28781166, PubMed:21549338). Enhances dihydrotestosterone-induced transactivation activity of AR, as well as dexamethasone-induced transactivation activity of NR3C1, but does not affect estrogen-induced transactivation. Identified in the spliceosome B complex (PubMed:28781166). Identified in the spliceosome C complex (PubMed:11991638). Associates with the U5 snRNP particle (PubMed:10788320). Component of the U4/U6-U5 tri-snRNP complex composed of the U4, U6 and U5 snRNAs and at least PRPF3, PRPF4, PRPF6, PRPF8, PRPF31, SNRNP200, TXNL4A, SNRNP40, DDX23, CD2BP2, PPIH, SNU13, EFTUD2, SART1 and USP39, LSm proteins LSm2-8 and Sm proteins (PubMed:16723661, PubMed:26912367, PubMed:28781166). Interacts with ARAF (PubMed:10848612). Interacts with AR and NR3C1, but not ESR1, independently of the presence of hormones (PubMed:12039962). Interacts with USH1G (PubMed:34023904). Localized in splicing speckles. Widely expressed. The disease may be caused by variants affecting the gene represented in this entry. Cells from RP60 patients show intron retention for pre-mRNA bearing specific splicing signals.