Anti-RPB4 antibodies enable researchers to detect and measure the RPB4 antigen in biological samples. This target is a reported synonym of the POLR2D gene, which encodes RNA polymerase II subunit D. This protein is known to function in transcription by RNA polymerase II, among other biological roles. The human version of RPB4 has a canonical amino acid length of 142 residues and a protein mass of 16.3 kilodaltons. It is reported to be localized in the nucleus of cells and widely expressed in many tissue types. RPB4 is a member of the Eukaryotic RPB4 RNA polymerase subunit protein family.