Required for pre-mRNA splicing as component of the activated spliceosome (   , ). Component of the U5 small nuclear ribonucleoprotein (snRNP) complex and the U4/U6-U5 tri-snRNP complex, building blocks 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