Component of the 17S U2 SnRNP complex of the spliceosome, a large ribonucleoprotein complex that removes introns from transcribed pre-mRNAs (PubMed:12234937, PubMed:32494006, PubMed:34822310, PubMed:36797247). The 17S U2 SnRNP complex (1) directly participates in early spliceosome assembly and (2) mediates recognition of the intron branch site during pre-mRNA splicing by promoting the selection of the pre-mRNA branch-site adenosine, the nucleophile for the first step of splicing (PubMed:32494006, PubMed:34822310). Within the 17S U2 SnRNP complex, DDX46 plays essential roles during assembly of pre-spliceosome and proofreading of the branch site (PubMed:34822310). {ECO:0000269|PubMed:12234937, ECO:0000269|PubMed:32494006, ECO:0000269|PubMed:34822310, ECO:0000269|PubMed:36797247}. This is the function of DDX46 (DEAD-box helicase 46, Ensembl gene identifier ENSG00000145833).