title: Characterization of a novel sulfated carbohydrate unit implicated in the carbohydrate-carbohydrate-mediated cell aggregation of the marine sponge Microciona prolifera.
abstract: Species-specific cell reaggregation in the marine sponge Microciona prolifera is mediated by an adhesion proteoglycan. Two interactions are involved in the process: a Ca(2+)-dependent homophilic binding between proteoglycan molecules and a Ca(2+)-independent binding between the molecule and cells. Both interactions are mediated by the glycan moieties of the proteoglycan. The interaction of the proteoglycan with itself has been characterized as a carbohydrate-carbohydrate interaction of multiple low affinity sites. The monoclonal antibodies Block 1 and Block 2 raised against the purified aggregation proteoglycan and selected for inhibition of aggregation bind to these glycans. In a previous report the structure, [formula: see text] was assigned to the oligosaccharide reacting with Block 1 antibody (Spillmann, D., Hård, K., Thomas-Oates, J., Vliegenthart, J. F. G., Misevic, G., Burger, M. M., and Finne, J. (1993) J. Biol. Chem. 268, 13378-13387). By the technique of attaching the water-soluble acid-degraded fragments to a lipid carrier for immunochemical detection and by chemical, enzymatic and spectroscopic methods the structure, [formula: see text] was assigned to the oligosaccharide reacting with the aggregation-blocking monoclonal antibody Block 2. The structure, [formula: see text] was assigned to a major nonreactive oligosaccharide, which outlined the molecular requirements of antibody binding of the two aggregation-associated epitopes. These data demonstrate that two different functional sites with distinct structural characteristics and antibody reactivities are involved in the reaggregation of sponge cells, a model of carbohydrate-carbohydrate-mediated cell interactions.
authors.affiliation: Department of Medical Biochemistry, University of Turku, Finland.
authors.forename: D
authors.initials: D
authors.lastname: Spillmann
authors.forename: J E
authors.initials: JE
authors.lastname: Thomas-Oates
authors.forename: J A
authors.initials: JA
authors.lastname: van Kuik
authors.forename: J F
authors.initials: JF
authors.lastname: Vliegenthart
authors.forename: G
authors.initials: G
authors.lastname: Misevic
authors.forename: M M
authors.initials: MM
authors.lastname: Burger
authors.forename: J
authors.initials: J
authors.lastname: Finne
mesh_terms: D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000032:analysis; D002448:Cell Adhesion / Q000502:physiology*; D002449:Cell Aggregation / Q000502:physiology*; D002852:Chromatography, Ion Exchange; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry / Q000302:isolation & purification; D011161:Porifera / Q000502:physiology*; D011509:Proteoglycans / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology
chemical_list: D002241:Carbohydrates; D009844:Oligosaccharides; D011509:Proteoglycans