Ribosomes, the organelles that catalyze protein synthesis, are composed of a small subunit (40S) and a large subunit (60S) that consist of over 80 distinct ribosomal proteins. Mammalian ribosomal proteins are encoded by multigene families that contain processed pseudogenes and one functional intron-containing gene within their coding regions. Ribosomal Protein S13 (RPS13), also known as 40S ribosomal protein S13, is a 151 amino acid cytoplasmic protein belonging to the Ribosomal Protein S15P family. The gene encoding Ribosomal Protein S13 maps to human chromosome 11p15.1 and mouse chromosome 7 F1 and contains multiple phosphorylated residues. Like most ribosomal proteins, Ribosomal Protein S13 exists as multiple processed pseudogenes that are scattered throughout the genome.