title: Interaction of high molecular weight kininogen binding proteins on endothelial cells.
abstract: Cell surface proteins reported to participate in the binding and activation of the plasma kinin-forming cascade includes gC1qR, cytokeratin 1 and u-PAR. Each of these proteins binds high molecular weight kininogen (HK) as well as Factor XII. The studies on the interaction of these proteins, using dot-blot analysis, revealed that cytokeratin 1 binds to both gC1qR and u-PAR while gC1qR and u-PAR do not bind to each other. The binding properties of these proteins were further analyzed by gel filtration. When biotinylated cytokeratin 1 was incubated with either gC1qR or u-PAR and gel filtered, a new, higher molecular weight peak containing biotin was observed indicating complex formation. The protein shift was also similar to the biotin shift. Further, immunoprecipitation of solubilized endo-thelial cell plasma membrane proteins with anti-gC1qR recovered both gC1qR and cytokeratin 1, but not u-PAR. Immunoprecipitation with anti-u-PAR recovered only u-PAR and cytokeratin 1. By competitive ELISA, gC1qR inhibits u-PAR from binding to cytokeratin 1; u-PAR inhibits gC1qR binding to a lesser extent and requires a 10-fold molar excess. Our data suggest that formation of HK (and Factor XII) binding sites along endothelial cell membranes consists of bimolecular com-plexes of gC1qR-cytokeratin 1 and u-PAR-cytokeratin 1, with gC1qR binding being favored.
authors.affiliation: Medical University of South Carolina, Department of Medicine, Division of Pulmonary/Critical Care, Allergy and Clinical Immunology, 96 Jonathan Lucas Street, P.O. Box 250623, Charleston, South Carolina 29425, USA. josephk@musc.edu
authors.forename: Kusumam
authors.initials: K
authors.lastname: Joseph
authors.forename: Baby G
authors.initials: BG
authors.lastname: Tholanikunnel
authors.forename: Berhane
authors.initials: B
authors.lastname: Ghebrehiwet
authors.forename: Allen P
authors.initials: AP
authors.lastname: Kaplan
mesh_terms: D001665:Binding Sites; D019921:Biotinylation; D015153:Blotting, Western; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002850:Chromatography, Gel; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D004797:Enzyme-Linked Immunosorbent Assay; D005174:Factor XII / Q000378:metabolism; D006801:Humans; D007633:Keratins / Q000737:chemistry / Q000378:metabolism; D019679:Kininogen, High-Molecular-Weight / Q000737:chemistry* / Q000378:metabolism; D007704:Kininogens / Q000097:blood; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000378:metabolism; D011951:Receptors, Complement / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D019679:Kininogen, High-Molecular-Weight; D007704:Kininogens; D008024:Ligands; D008562:Membrane Glycoproteins; C524898:PLAUR protein, human; D011956:Receptors, Cell Surface; D011951:Receptors, Complement; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins; C032402:complement 1q receptor; D007633:Keratins; D005174:Factor XII