part of part of in taxon output_of output of output of extracellular space immunoglobulin complex secretion by cell immunoglobulin complex, circulating antibody Note that an immunoglobulin complex has the function of antigen binding if a suitable antigen is available. cellular_component protein Wikipedia:Antibody GO:0042571 An immunoglobulin complex that is secreted into extracellular space and found in mucosal areas or other tissues or circulating in the blood or lymph. In its canonical form, a circulating immunoglobulin complex is composed of two identical heavy chains and two identical light chains, held together by disulfide bonds. Some forms of are polymers of the basic structure and contain additional components such as J-chain and the secretory component.