Involved in pre-mRNA splicing as component of the spliceosome (PubMed:11991638, PubMed:28076346, PubMed:28502770, PubMed:28781166, PubMed:32494006). Associated with sn-RNP U2, where it contributes to the binding of stem loop IV of U2 snRNA (PubMed:32494006, PubMed:9716128). {ECO:0000269|PubMed:11991638, ECO:0000269|PubMed:28076346, ECO:0000269|PubMed:28502770, ECO:0000269|PubMed:28781166, ECO:0000269|PubMed:32494006, ECO:0000269|PubMed:9716128}. This is the function of SNRPB2 (small nuclear ribonucleoprotein polypeptide B2, ENSG00000125870).