title: Evidence that a 210,000-molecular-weight glycoprotein (GP 210) serves as a platelet Fc receptor.
abstract: We previously identified a 210,000-mol-wt platelet glycoprotein (GP 210) that is missing from Bernard-Soulier platelets, and found that an antibody against GP 210 inhibits ristocetin-induced platelet agglutination. We now show by immunoblotting that GP 210 binds heat-aggregated rabbit and human IgG, as well as keyhole limpet hemocyanin (KLH)-anti-KLH and ovalbumin (OA)-anti-OA immune complexes. Immune complex binding to GP 210 was preserved on chymotrypsin-treated platelets that lacked glycoprotein Ib (GP Ib). In contrast, ristocetin-induced platelet agglutination resulted in disappearance of immunologically detectable GP 210 and loss of immune complex binding, even though GP Ib remained intact. Purified Fc fragments inhibited binding of anti-GP 210 antibody to intact platelets and to GP 210 on immunoblots. The Fc fragments also blocked immune complex binding to GP 210. Conversely, anti-GP 210 antiserum and F(ab)2 fragments inhibited binding of fluorescein-labeled Fc fragments to intact platelets. We conclude that GP 210 functions as a platelet Fc receptor.
mesh_terms: D006801:Humans; D000906:Antibodies / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000276:immunology; D001606:Bernard-Soulier Syndrome / Q000097:blood; D001792:Blood Platelets / Q000187:drug effects; D002918:Chymotrypsin / Q000494:pharmacology; D003902:Detergents / Q000494:pharmacology; D008970:Molecular Weight; D010980:Platelet Membrane Glycoproteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology; D011961:Receptors, Fc / Q000276:immunology / Q000302:isolation & purification; D012310:Ristocetin / Q000494:pharmacology; D028861:Nuclear Pore Complex Proteins
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D002918:Chymotrypsin; D003902:Detergents; D010980:Platelet Membrane Glycoproteins; D011961:Receptors, Fc; D012310:Ristocetin; C063865:NUP210 protein, human; D028861:Nuclear Pore Complex Proteins