Anti-regulatory factor X3 antibodies are used in the immunodetection of the protein encoded by the RFX3 gene. In humans, the canonical protein has a reported length of 749 amino acid residues and a mass of 83.5 kDa. Its subcellular localization is in the nucleus. Alternative splicing is reported to yield 3 different isoforms for this protein. A member of the RFX protein family, it is known to be a transcription factor required for ciliogenesis and islet cell differentiation during endocrine pancreas development. Other names for this target antigen include DNA binding protein RFX3, regulatory factor X, 3 (influences HLA class II expression), and transcription factor RFX3.