Anti-keratin 33B, type I antibodies enable researchers to detect and measure the keratin 33B, type I antigen in biological samples. This target is a reported synonym of the KRT33B gene, which encodes keratin 33B. This protein is known to function in pathways of aging and epithelial cell differentiation, among other biological roles. The human version of keratin 33B, type I has a canonical amino acid length of 404 residues and a protein mass of 46.2 kilodaltons. It is reported to be notably expressed in the hair. Other names for this target antigen include HA3II, Ha-3II, and K33B.