Anti-L21 antibodies enable researchers to detect and measure the L21 antigen in biological samples. This target is a reported synonym of the RPL21 gene, which encodes ribosomal protein L21. This protein is known to function in protein translation, among other biological roles. The human version of L21 has a canonical amino acid length of 160 residues and a protein mass of 18.6 kilodaltons. It is reported to be localized in the ER and cytoplasm of cells and widely expressed in many tissue types. L21 is a member of the Eukaryotic ribosomal protein eL21 protein family.