Anti-bis1 antibodies are protein reagents that detect specific antigens. The bis1 antigen is another term for the human protein ess-2 splicing factor homolog, encoded by the ESS2 gene. The protein is suspected to be involved in pre-mRNA splicing. Canonically, it has an amino acid length of 476 residues and a mass of 52.6 kilodaltons. Its subcellular localization is in the nucleus and it is reported to be highly expressed in the heart, brain and skeletal muscle. The bis1 protein is a member of the ESS2 protein family.