title: Specific adsorption of a platelet membrane glycoprotein by human insoluble collagen.
abstract: A platelet membrane glycoprotein, 61 kDa, has been identified, which binds specifically to insoluble collagen. The detection of this protein was accomplished by incubating radiolabeled Triton-solubilized platelet supernatant with insoluble collagen, and, after washing the collagen pellet, extracting the 61-kDa glycoprotein from the pellet with sodium dodecyl sulfate buffer. The optimal conditions for specific binding were incubation of 120 micrograms of total platelet supernatant protein with 2 mg of collagen at 4 degrees C for 0.5 h in 0.5 ml of the incubating buffer (20 mM Tris, 150 mM NaCl, 2 mM CaCl2, 1 mM MgCl2, and 0.2% Triton, pH 7.4). The 61-kDa glycoprotein is cleaved by trypsin into a major peptide (44 kDa) and a smaller peptide(s) linked together by disulfide bonds in a molecule which still binds to collagen. When intact platelets are treated first with trypsin and then with dithiothreitol, the 44-kDa peptide is released and was shown to bind to collagen. We conclude that the 61-kDa glycoprotein is a platelet membrane protein which specifically interacts through its extracellular domain with insoluble collagen, and, thus, must be considered as a possible component of the initial platelet-matrix adhesion process which leads to platelet aggregation in vivo.
mesh_terms: D000327:Adsorption; D003094:Collagen / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005470:Fluorometry; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008970:Molecular Weight; D010980:Platelet Membrane Glycoproteins; D013696:Temperature; D014357:Trypsin / Q000378:metabolism
chemical_list: D006023:Glycoproteins; D008565:Membrane Proteins; D010980:Platelet Membrane Glycoproteins; D003094:Collagen; D014357:Trypsin; D004229:Dithiothreitol