Asn-linked oligosaccharide-dependent interaction between laminin and gp120/140. An alpha 6/beta 1 integrin.
Receptor-mediated recognition and adhesion to laminin, a specific glycoprotein from basement membranes, exert an important role in many biological phenomena. Studying cell surface proteins of B16-F10, a metastatic murine melanoma cell line, we identified a 120-140 kDa glycoprotein (gp120/140) that binds laminin. This glycoprotein was recognized by a polyclonal antibody raised against the human fibronectin receptor beta 1-integrin chain, as well as immunoprecipitated by an anti-alpha 6 chain (monoclonal antibody GoH3), characterizing it as an alpha 6/beta 1-integrin. Its binding to laminin was specific and displayed moderate affinity, as its apparent dissociation constant was 18 nM. To characterize the influence of carbohydrate moieties on the laminin-gp120/140 interaction, metaperiodate oxidation, metabolic inhibition of glycosylation, and enzymatic deglycosylation studies were performed. Our results indicate that gp120/140 Asn-linked oligosaccharides play a part in this interaction. Reciprocally, both metaperiodate and N-glycanase treatment of native laminin reduced its binding to gp120/140, characterizing the latter as a lectin-like molecule. These results point to glycosylation processes as a possible mechanism for variable binding specificity profiles among integrins.
Chammas
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Ludwig Institute for Cancer Research, São Paulo Branch, Brazil.
Veiga
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Line
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Potocnjak
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Brentani
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D000818:Animals; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006023:Glycoproteins / Q000378:metabolism; D016023:Integrins / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism*; D008546:Melanoma, Experimental / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D009844:Oligosaccharides / Q000378:metabolism*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D014407:Tumor Cells, Cultured; D014415:Tunicamycin / Q000494:pharmacology
D006023:Glycoproteins; D016023:Integrins; D007797:Laminin; D009844:Oligosaccharides; D014415:Tunicamycin