Anti-CLDN21 antibodies enable researchers to detect and measure the CLDN21 antigen in biological samples. This target is a reported synonym of the CLDN22 gene, which encodes claudin 22. This protein is known to function in cell adhesion, among other biological roles. The human version of CLDN21 has a canonical amino acid length of 220 residues and a protein mass of 24.5 kilodaltons. It is reported to be localized in the cell membrane of cells. CLDN21 is a member of the Claudin protein family.