Anti-HA3II antibodies are protein reagents that detect specific antigens. The HA3II antigen is another term for the human protein keratin 33B, encoded by the KRT33B gene. The protein is known to function in pathways of aging and epithelial cell differentiation, among other biological roles. Canonically, it has an amino acid length of 404 residues and a mass of 46.2 kilodaltons. It is expressed in the hair. The HA3II protein is a member of the Intermediate filament protein family. Other alias names for HA3II include K33B.