40S ribosomal protein S3a, also known as RPS3A, belongs to the S3AE family of ribosomal proteins. Ribosomes, the organelles that catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit. Together these subunits are composed of 4 RNA species and approximately 80 structurally distinct proteins. This protein is a ribosomal protein that is a component of the 40S subunit and is located in the cytoplasm. Disruption of the gene encoding rat ribosomal protein S3a, also named v-fos transformation effector protein, in v-fos-transformed rat cells results in reversion of the transformed phenotype.