Anti-Z39IG antibodies are used in antigen-specific immunodetection in biological samples. The target Z39IG is a known alias name of the protein V-set and immunoglobulin domain containing 4, encoded by the VSIG4 gene in humans. This protein has a canonical amino acid length of 399 residues and a mass of 44 kDa. It is localized to the membrane of the cell. In terms of tissue expression, it is found to be highly expressed in several fetal tissues. Other synonyms for Z39IG include CRIg and CRIg.