Cellular component

dimeric IgA antibody

A protein complex composed of two monomeric IgA immunoglobulin complexes linked through both direct disulfide bonds and through a disulfide binded monomer of J chain acting as a bridge. Each IgA monomer consists of two identical immunoglobulin heavy chains of an IgA isotype and two identical immunoglobulin light chains, held together by disulfide bonds. Dimeric IgA is sometimes complexed additionally with secretory component, and present in the extracellular space, in mucosal areas or other tissues, or circulating in the blood or lymph.

Note that an IgA immunoglobulin complex has the function of antigen binding if a suitable antigen is available. Dimeric IgA is by far the most common form of polymeric IgA. In human only the IgA1 isotype is capable of a dimeric form.