title: CD31 (PECAM-1) exists as a dimer and is heavily N-glycosylated.
abstract: CD31 (PECAM-1) is a highly abundant cell surface glycoprotein expressed on hemopoietic and endothelial cells where it functions as a homophilic adhesion and signaling receptor. Since dimerization and appropriate glycosylation are important features in the regulation of cell surface interactions and signal transduction, we studied the pattern of glycosylation as well as the ability of CD31 to undergo dimerization, both in solution and when expressed on cell membranes. CD31 is heavily glycosylated, with an approximate carbohydrate content of 21%. Nineteen neutral and thirteen sialylated glycans were identified. Ultracentrifugation analysis showed that soluble recombinant CD31 exists in equilibrium between a monomer and a dimer with an approximate dissociation constant of 12.5 microM. Chemical cross-linking studies of both soluble and membrane-expressed CD31 confirmed that CD31 exists as a dimer. These studies suggest that, like E-cadherin, PECAM-dimerization is likely to play a role in CD31 adhesion and signaling.
authors.affiliation: Cell Adhesion Laboratory, Institute of Molecular Medicine, Headington, OX3 9DU, United Kingdom.
authors.forename: J P
authors.initials: JP
authors.lastname: Newton
authors.forename: A P
authors.initials: AP
authors.lastname: Hunter
authors.forename: D L
authors.initials: DL
authors.lastname: Simmons
authors.forename: C D
authors.initials: CD
authors.lastname: Buckley
authors.forename: D J
authors.initials: DJ
authors.lastname: Harvey
mesh_terms: D000818:Animals; D001483:Base Sequence; D002240:Carbohydrate Sequence; D002448:Cell Adhesion; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents; D017931:DNA Primers / Q000235:genetics; D019281:Dimerization; D006031:Glycosylation; D006801:Humans; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D012996:Solutions; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D003432:Cross-Linking Reagents; D017931:DNA Primers; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D011134:Polysaccharides; D011994:Recombinant Proteins; D012996:Solutions