Component of the large ribosomal subunit. The ribosome is a large ribonucleoprotein complex responsible for the synthesis of proteins in the cell. {ECO:0000269|PubMed:23636399, ECO:0000269|PubMed:32669547}. This is the function of RPL15 (ribosomal protein L15, Ensembl gene identifier ENSG00000174748).