Anti-p200 antibodies enable researchers to detect and measure the p200 antigen in biological samples. This target is a reported synonym of the HEATR5B gene, which encodes HEAT repeat containing 5B. This protein is known to function in endocytosis and protein localization, among other biological roles. The human version of p200 has a canonical amino acid length of 2071 residues and a protein mass of 224.3 kilodaltons, although 3 isoforms have been identified. It is reported to be localized in the cytoplasmic vesicles and cytoplasm of cells and widely expressed in many tissue types. p200 is a member of the HEATR5 protein family.