Plays a role in pre-mRNA splicing as a core component of the spliceosomal U1, U2, U4 and U5 small nuclear ribonucleoproteins (snRNPs), the building blocks of the spliceosome (    ). Component of both the pre-catalytic spliceosome B complex and activated spliceosome C complexes ( , ). As a component of the minor spliceosome, involved in the splicing of U12-type introns in pre-mRNAs (, ). As part of the U7 snRNP it is involved in histone pre-mRNA 3'-end processing (By similarity).
Subcellular locations: Cytoplasm, Cytosol, Nucleus
SMN-mediated assembly into core snRNPs occurs in the cytosol before SMN-mediated transport to the nucleus to be included in spliceosomes.