Biomaterial Database

Identification of the fibrinogen receptor on human platelets by photoaffinity labeling. 1982

J S Bennett, and G Vilaire, and D B Cines

Fibrinogen binding to receptors on stimulated platelets is a prerequisite for platelet aggregation. In order to identify the platelet fibrinogen receptor, we modified fibrinogen with the photoreactive, heterobifunctional cross-linking reagent methyl 4-azidobenzoimidate (MABI). MABI-fibrinogen was fully clottable and able to support platelet aggregation. To photoaffinity label the fibrinogen receptor, gel-filtered human platelets were incubated at 37 degrees C in the dark with 200 micrograms/ml of MABI-fibrinogen, 10 microM ADP, and 0.5 mM calcium. Irradiation of these platelets with ultraviolet light resulted in the incorporation of MABI-fibrinogen into the platelet surface. Incorporation could be prevented by excess native fibrinogen suggesting that MABI-fibrinogen had interacted with the fibrinogen receptor before photolysis. Examination of the irradiated platelets by sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed that the photoactivated MABI-fibrinogen had been incorporated into a 105,000 molecular weight membrane polypeptide that also contained the PlA1 antigen. Thus, this polypeptide has the characteristics of the membrane glycoprotein IIIa. Previous studies have shown that thrombasthenic platelets lack this glycoprotein and fail to bind fibrinogen after stimulation by ADP. Consequently, our data suggest that glycoprotein IIIa constitutes at least one component of the platelet fibrinogen receptor.

UI	MeSH Term	Description	Entries
D007096	Imidoesters	Esters of the hypothetical imidic acids. They react with amines or amino acids to form amidines and are therefore used to modify protein structures and as cross-linking agents.	Imidates
D007106	Immune Sera	Serum that contains antibodies. It is obtained from an animal that has been immunized either by ANTIGEN injection or infection with microorganisms containing the antigen.	Antisera,Immune Serums,Sera, Immune,Serums, Immune
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D010980	Platelet Membrane Glycoproteins	Surface glycoproteins on platelets which have a key role in hemostasis and thrombosis such as platelet adhesion and aggregation. Many of these are receptors.	PM-GP,Platelet Glycoprotein,Platelet Membrane Glycoprotein,PM-GPs,Platelet Glycoproteins,Glycoprotein, Platelet,Glycoprotein, Platelet Membrane,Glycoproteins, Platelet,Glycoproteins, Platelet Membrane,Membrane Glycoprotein, Platelet,Membrane Glycoproteins, Platelet,PM GP
D011956	Receptors, Cell Surface	Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands.	Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D001792	Blood Platelets	Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.	Platelets,Thrombocytes,Blood Platelet,Platelet,Platelet, Blood,Platelets, Blood,Thrombocyte
D002462	Cell Membrane	The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.	Plasma Membrane,Cytoplasmic Membrane,Cell Membranes,Cytoplasmic Membranes,Membrane, Cell,Membrane, Cytoplasmic,Membrane, Plasma,Membranes, Cell,Membranes, Cytoplasmic,Membranes, Plasma,Plasma Membranes
D005340	Fibrinogen	Plasma glycoprotein clotted by thrombin, composed of a dimer of three non-identical pairs of polypeptide chains (alpha, beta, gamma) held together by disulfide bonds. Fibrinogen clotting is a sol-gel change involving complex molecular arrangements: whereas fibrinogen is cleaved by thrombin to form polypeptides A and B, the proteolytic action of other enzymes yields different fibrinogen degradation products.	Coagulation Factor I,Factor I,Blood Coagulation Factor I,gamma-Fibrinogen,Factor I, Coagulation,gamma Fibrinogen
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000345	Affinity Labels	Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.	Affinity Labeling Reagents,Labeling Reagents, Affinity,Labels, Affinity,Reagents, Affinity Labeling