Laminin-5r is a basement membrane component that promotes rapid adhesion and hemidesmosome formation in epithelial cells. We raised monoclonal antibodies and identified their corresponding epitopes on the constituent chains of laminin-5r by western blotting. Using a combination of immunoprecipitation and ELISA assays, we determined that these epitopes are differentially exposed on two forms of the laminin-5r heterotrimer: soluble (passively adsorbed onto plastic) and cell-associated. Antibody 5C5 epitope is exposed on the cell-associated form, but not the soluble/passively adsorbed form of laminin-5r. Epitopes reactive with antibodies CM6, FM3, and TR1 are also preferentially exposed on cell-associated laminin-5r, such that reactivity of these antibodies with the cell-associated form is fourfold higher than with the soluble/passively adsorbed form in ELISA assays. Incubation of passively adsorbed laminin-5r with the human epithelial cell line SCC12 induced exposure of 5C5 and CM6, FM3, or TR1 epitopes. These data suggest that cells actively modify laminin-5r, perhaps during matrix assembly, and that the 5C5 epitope may serve as a marker for assembled laminin-5r matrix.
Changes in expression of monoclonal antibody epitopes on laminin-5r induced by cell contact
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G. Plopper, J. Falk-Marzillier, S. Glaser, M. Fitchmun, G. Giannelli, T. Romano, J.C. Jones, V. Quaranta; Changes in expression of monoclonal antibody epitopes on laminin-5r induced by cell contact. J Cell Sci 1 July 1996; 109 (7): 1965–1973. doi: https://doi.org/10.1242/jcs.109.7.1965
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