. "\"A protein complex composed of two identical immunoglobulin heavy chains of an IgG isotype and two identical immunoglobulin light chains, held together by disulfide bonds, and present in the extracellular space, in mucosal areas or other tissues, or circulating in the blood or lymph.\" [GOC:add, ISBN:0781765196]" . . "IgG immunoglobulin complex, circulating" . "Note that an IgG immunoglobulin complex has the function of antigen binding if a suitable antigen is available. Also, IgG isotypes vary by species." . . . "IgG antibody" . "IgG1 antibody" . "IgG2 antibody" . "IgG2a antibody" . "IgG2b antibody" . "IgG2c antibody" . "IgG3 antibody" . "IgG4 antibody" .