[Term] id: PR:000050312 name: IgG4 immunoglobulin complex, circulating (human) def: "An IgG4 immunoglobulin complex (human) that is composed of two immunoglobulin heavy chains of an IgG4 isotype of the secretory isoform and two immunoglobulin light chains (kappa or lambda), held together by disulfide bonds and present in the extracellular space, in mucosal areas or other tissues, or circulating in the blood or lymph. Note that secreted IgG4 often undergoes half-molecule exchange (exchange of one heavy chain-light chain arm for another) to form bivalent complexes (two independent binding sites) that are functionally molevalent in most biological situations." [PRO:ADD, PMID:25368619, GOC:add] comment: Category=organism-complex. Requested by=HIPC. Requested by=CL. synonym: "hIgG4/circulating" EXACT PRO-short-label [PRO:ADD, GOC:add] synonym: "IgG4 antibody (human)" EXACT [PRO:ADD, GOC:add] synonym: "IgG antibody (human)" BROAD [PRO:ADD, GOC:add] is_a: PR:000050308 ! IgG4 immunoglobulin complex (human) relationship: has_component PR:000050300 {cardinality="2"} ! IgG4 heavy chain protein, secretory isoform (human) relationship: has_component PR:000050183 {cardinality="2"} ! immunoglobulin light chain protein (human) relationship: only_in_taxon NCBITaxon:9606 ! Homo sapiens