Anti-4F9 antibodies enable researchers to detect and measure the 4F9 antigen in biological samples. This target is a reported synonym of the CD82 gene, which encodes CD82 molecule. This protein is reported to associate with CD4 or CD8 and delivers costimulatory signals for the TCR/CD3 pathway. The human version of 4F9 has a canonical amino acid length of 267 residues and a protein mass of 29.6 kilodaltons, although 2 isoforms have been identified. It is reported to be localized in the cell membrane of cells and notably expressed in many tissues, such as the placenta and skin. This target antigen may also be known as C33. ELISA, Western Blot, and Immunohistochemistry are common applications for 4F9 antibodies.