Part of the small subunit (SSU) processome, first precursor of the small eukaryotic ribosomal subunit. During the assembly of the SSU processome in the nucleolus, many ribosome biogenesis factors, an RNA chaperone and ribosomal proteins associate with the nascent pre- rRNA and work in concert to generate RNA folding, modifications, rearrangements and cleavage as well as targeted degradation of pre- ribosomal RNA by the RNA exosome (PubMed:34516797). Involved in pre- mRNA splicing as component of the spliceosome (PubMed:28781166). Binds to the 5'-stem-loop of U4 snRNA and thereby contributes to spliceosome assembly (PubMed:10545122, PubMed:17412961). The protein undergoes a conformational change upon RNA-binding (PubMed:10545122, PubMed:17412961, PubMed:28781166). Core component of box C/D small nucleolar ribonucleoprotein (snoRNP) complexes that function in methylation of multiple sites on ribosomal RNAs (rRNAs) and messenger RNAs (mRNAs) (PubMed:39570315). {ECO:0000269|PubMed:10545122, ECO:0000269|PubMed:17412961, ECO:0000269|PubMed:28781166, ECO:0000269|PubMed:34516797, ECO:0000269|PubMed:39570315}. This is the function of Ensembl gene identifier ENSG00000100138 (SNU13, small nuclear ribonucleoprotein 13).