Required for pre-mRNA splicing as component of the spliceosome, including pre-catalytic, catalytic and post-catalytic spliceosomal complexes (    ). Component of the U5 snRNP and the U4/U6-U5 tri-snRNP complex, a building block of the spliceosome . As a component of the minor spliceosome, involved in the splicing of U12-type introns in pre-mRNAs (Probable).
Subcellular locations: Nucleus