Ready-to-use ELISA kits are available for the detection of Z39IG, an alias of the protein, V-set and immunoglobulin domain containing 4. The official gene symbol is VSIG4. The protein, with a mass of 44 kDa and length of 399 residues, is reported to be membrane-associated. It may be known by other names, including: Z39IG, protein Z39Ig, complement receptor of the immunoglobulin superfamily, Ig superfamily protein, and V-set and immunoglobulin domain-containing protein 4.