title: Kininogen binding protein p33/gC1qR is localized in the vesicular fraction of endothelial cells.
abstract: The endothelial protein p33/gC1qR is thought to mediate the assembly of components of the kinin-forming and complement-activating pathways on the surface of cardiovascular cells. FACS analysis of intact human umbilical vein endothelial cells using specific antibodies to p33 revealed a minor fluorescence on the cell surface whereas permeabilized cells showed a bright fluorescence indicative of an intracellular localization of p33. Immunostaining of fixed cells confirmed the predominant intracellular localization of p33. Fractionation studies demonstrated that the vesicular but not the membrane fraction of EA.hy926 cells is rich in p33. We conclude that externalization of p33 must precede its complex formation with target proteins on the endothelial cell surface.
authors.affiliation: Institute for Physiological Chemistry and Pathobiochemistry, Johannes Gutenberg University at Mainz, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Dedio
authors.forename: W
authors.initials: W
authors.lastname: Müller-Esterl
mesh_terms: D002352:Carrier Proteins; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D006801:Humans; D018960:Hyaluronan Receptors; D007106:Immune Sera; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011951:Receptors, Complement / Q000378:metabolism*
chemical_list: C087299:C1QBP protein, human; D002352:Carrier Proteins; D018960:Hyaluronan Receptors; D007106:Immune Sera; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011951:Receptors, Complement; C032402:complement 1q receptor