Anti-E4 antibodies are protein reagents that detect specific antigens. The E4 antigen is another term for the human protein ubiquitination factor E4A, encoded by the UBE4A gene. The protein is reported to be a ubiquitin-protein ligase that probably functions as an E3 ligase in conjunction with specific E1 and E2 ligases. Canonically, it has an amino acid length of 1066 residues and a mass of 122.6 kilodaltons. Its subcellular localization is in the cytoplasm and it is widely expressed in many tissue types. The E4 protein is a member of the Ubiquitin conjugation factor E4 protein family. Other alias names for E4 include NEDHMS and UBOX2. These E4 antibodies are widely used in ELISA experiments, among other applications.