PURIFICATION AND CHARACTERIZATION OF THE D-MANNOSE RECEPTOR FROM J774-MOUSE MACROPHAGE CELLS

Macrophages display on their cell surface a D-mannose-specific receptor which facilitates the scavenging of certain pathogens and deleterious macromolecules from the extracellular fluid as part of the host defense mechanism. The mouse D-mannose receptor was purified from J774 E macrophages and an antiserum was generated against the receptor protein. In mouse macrophages, the newly synthesized receptor has an M(r) of 157 000 Da and rapidly matures to a protein with an M(r) of 172 000 Da. Both forms of the receptor protein are tightly associated with cell membranes. The receptor is found in a number of mouse macrophage cell types but is not present in mouse fibroblasts. An assay was developed to characterize D-mannose receptor-ligand binding based on immunoprecipitation of the detergent-solubilized receptor protein. The dissociation constant, determined for receptor and the neoglycoprotein D-mannose-BSA, was 1.67 nm. Receptor-ligand binding was calcium and pH dependent. Monosaccharides, such as D-mannose and L-fucose, partially inhibited receptor binding to the ligand D-mannose-BSA.