immunoglobulin complex IgY immunoglobulin complex cellular_component A protein complex composed of two identical immunoglobulin heavy chains of the IgY isotype and two identical immunoglobulin light chains, held together by disulfide bonds. An IgY immunoglobulin complex may be embedded in the plasma membrane or present in the extracellular space, in mucosal areas or other tissues, or circulating in the blood or lymph. 2010-03-24T01:44:53Z mah GO:0071760 Note that an IgY immunoglobulin complex has the function of antigen binding if a suitable antigen is available. Note that IgY is found in amphibians, reptiles, and birds.