Anti-Oppo1 antibodies enable researchers to detect and measure the Oppo1 antigen in biological samples. This target is a reported synonym of the ODF4 gene, which encodes outer dense fiber of sperm tails 4. This protein is known to function in cell differentiation and spermatogenesis, among other biological roles. The human version of Oppo1 has a canonical amino acid length of 257 residues and a protein mass of 29.2 kilodaltons. It is reported to be localized in the membrane of cells and notably expressed in the testis.