Anti-PR/SET domain 9 antibodies are used in the immunodetection of the protein encoded by the PRDM9 gene. In humans, the canonical protein has a reported length of 894 amino acid residues and a mass of 103.4 kDa. Its subcellular localization is in the nucleus. A member of the Class V-like SAM-binding methyltransferase protein superfamily, it is a known histone methyltransferase that sequentially mono-, di-, and tri-methylates both 'Lys-4' (H3K4) and 'Lys-36' (H3K36) of histone H3 to produce respectively trimethylated 'Lys-4' (H3K4me3) and trimethylated 'Lys-36' (H3K36me3) histone H3 and plays a key role in meiotic prophase by determining hotspot localization thereby promoting meiotic recombination. Post-translational modifications have been described, including methylation. Other names for this target antigen include PR domain 9, PR domain containing 9, PR domain zinc finger protein 9, [histone H3]-lysine36 N-trimethyltransferase PRDM9, and histone-lysine N-methyltransferase PRDM9.