RRS1 is involved in ribosomal large subunit assembly. UniProt annotates it as a possible regulator of the localisation of the 5S ribonucleoprotein particle (5S RNP) to the nucleolus, the site where ribosomal subunits are built. NCBI Gene records that RRS1 enables 5S rRNA binding activity, which fits a role in handling the 5S RNP during large subunit formation.

The protein is also linked to protein localisation to the nucleolus, consistent with its proposed role in directing the 5S RNP there. Beyond ribosome assembly, NCBI Gene lists involvement in mitotic metaphase chromosome alignment. The protein is located in the nucleolus and in condensed nuclear chromosome, so it is found both in the ribosome-building compartment and on chromosomes. Researchers studying the RRS1 protein therefore often consider it in the context of both nucleolar function and mitosis.

The RRS1 gene is named for its role as a regulator of ribosome synthesis and is the human homologue of a yeast factor, as reflected in its previous HGNC names, such as RRS1 ribosome biogenesis regulator homolog (S. cerevisiae). It has also been listed under the alias KIAA0112. Mouse and rat each have an orthologue named Rrs1, which allows comparative work in rodent systems.