title: Cultured human endothelial cells synthesize a plasma membrane protein complex immunologically related to the platelet glycoprotein IIb/IIIa complex.
abstract: We have previously demonstrated that endothelial cells synthesize a plasma membrane protein indistinguishable from platelet glycoprotein (GP) IIa. The present study provides evidence for a further analogy between the platelet and the endothelial cell membrane by showing that cultured endothelial cells also synthesize a membrane protein complex immunologically related to the platelet GP IIb/GP IIIa complex. This evidence is based on the following observations: (1) C17, a murine monoclonal antiplatelet GP IIIa antibody, consistently precipitates two proteins, apparent molecular weights, respectively, 115,000 and 125,000 reduced and 95,000 and 135,000 nonreduced, from metabolically (35S-methionine) as well as surface 125I-labeled cultured human endothelial cells; (2) upon crossed immunoelectrophoresis of solubilized endothelial cells against a polyclonal rabbit antiplatelet antiserum and 125I-labeled C17 IgG, a single precipitate of the protein(s) recognized by C17 is observed. As judged by their mobility in 9% polyacrylamide gels, both endothelial proteins appear to have a somewhat larger molecular weight than their platelet counterparts. Patterns obtained by crossed immunoelectrophoresis are also indicative of a difference in electrophoretic behavior of the platelet GP IIb/IIIa complex and the endothelial cell protein complex.
mesh_terms: D001792:Blood Platelets / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004727:Endothelium / Q000166:cytology / Q000378:metabolism*; D006023:Glycoproteins / Q000096:biosynthesis*; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D008565:Membrane Proteins / Q000096:biosynthesis*; D010980:Platelet Membrane Glycoproteins; D014471:Umbilical Veins
chemical_list: D006023:Glycoproteins; D008565:Membrane Proteins; D010980:Platelet Membrane Glycoproteins