Anti-NOP2/Sun RNA methyltransferase 5 antibodies are used for the immunodetection of the protein encoded by the NSUN5 gene. In humans, the canonical protein has a reported length of 429 amino acid residues and a mass of 46.7 kDa. Its subcellular localization is in the nucleus. Alternative splicing is reported to yield 5 different isoforms for this protein. It is ubiquitously expressed across many tissue types. A member of the RsmB/NOP protein family, it is reported to be a S-adenosyl-L-methionine-dependent methyltransferase that specifically methylates the C(5) position of cytosine 3782 (m5C3782) in 28S rRNA. Other names for this target antigen include NOL1-related protein, NOL1/NOP2/Sun domain family member 5, NOP2/Sun RNA methyltransferase family member 5, NOP2/Sun domain family, member 5, and 28S rRNA (cytosine-C(5))-methyltransferase. Gene orthologs have been identified in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.