RPS15 is a structural component of the small ribosomal subunit. The ribosome is a large ribonucleoprotein complex responsible for the synthesis of proteins in the cell. Ribosomes catalyse this process and consist of a small 40S subunit and a large 60S subunit, which together are composed of four RNA species and approximately 80 structurally distinct proteins. The RPS15 protein is one of those proteins and sits in the 40S subunit.

The RPS15 gene encodes a protein of the S19P family of ribosomal proteins, designated uS19 under the universal ribosomal protein nomenclature. HGNC places it in the S ribosomal proteins gene group. The protein is located in the cytoplasm, where ribosomes carry out translation. As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of this gene dispersed through the genome, and alternative splicing results in multiple transcript variants. Mouse and rat each have an ortholog named Rps15.

The protein is also known by the aliases RIG, S15, MGC111130 and uS19. In disease-related context, the RPS15 gene has been found to be activated in various tumours, such as insulinomas, esophageal cancers and colon cancers. Researchers studying RPS15 therefore work across ribosome biology, translation and cancer-related gene expression, often alongside other ribosomal proteins of the small subunit.