title: Monoclonal antibodies against a glycoprotein localized in coated pits and endocytic vesicles inhibit alpha 2-macroglobulin binding and uptake.
abstract: Eight monoclonal antibodies, all IgG2a, which recognize a 180/90-kDa glycoprotein similar in properties to the receptor for alpha 2-macroglobulin of mouse embryo 3T3 cell plasma membranes, have been tested for their effect on the binding and uptake of alpha 2-macroglobulin by live cells. One antibody directly inhibited binding of 125I-alpha 2-macroglobulin under conditions in which 125I-transferrin binding to the transferrin receptor was unaffected. Another monoclonal antibody decreased alpha 2-macroglobulin binding when preincubated with cells at 37 degrees C. This antibody was also capable of specifically binding to ligand-receptor complexes formed by preincubating 125I-alpha 2-macroglobulin with detergent extracts of Swiss 3T3 cells. Immunoelectron microscopy showed that the 180/90-kDa glycoprotein was localized in coated pits of the cell surface and in intracellular endocytic vesicles (receptosomes/endosomes). The data suggest that the 180/90-kDa glycoprotein is a component of the receptor for alpha 2-macroglobulin.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D002462:Cell Membrane / Q000276:immunology* / Q000648:ultrastructure; D002478:Cells, Cultured; D003034:Coated Pits, Cell-Membrane / Q000276:immunology* / Q000648:ultrastructure; D004705:Endocytosis; D011992:Endosomes / Q000276:immunology*; D006023:Glycoproteins / Q000276:immunology / Q000302:isolation & purification*; D006801:Humans; D007074:Immunoglobulin G; D007700:Kinetics; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D051379:Mice; D008815:Mice, Inbred Strains; D008854:Microscopy, Electron; D011971:Receptors, Immunologic / Q000378:metabolism*; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D006023:Glycoproteins; D007074:Immunoglobulin G; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D011971:Receptors, Immunologic; D000511:alpha-Macroglobulins