title: Solubilization and characterization of a low-affinity histamine-binding site on human blood mononuclear cells.
abstract: The extract of human peripheral blood lymphocytes and monocytes treated with Triton X-100, in direct- and competitive-binding studies, with 10(-6)-10(-2) M [14C]histamine contained a low-affinity binding site whose dissociation constant (Kd 1.8 X 10(-4) M) was commensurate with the concns of histamine (10(-6)-10(-3) M) that result from mast cell and basophil degranulation. Binding was enhanced by millimolar concns of divalent cations and by raising the incubation temp from 4 to 37 degrees C. It was inhibited by trypsin, EDTA, agents interacting with thiol groups, and by Triton X-100 concns greater than 0.2%. Thus a low-affinity histamine receptor that maintains its ligand-binding properties after solubilization from the cell surface was identified.
mesh_terms: D001667:Binding, Competitive; D002118:Calcium; D002462:Cell Membrane / Q000032:analysis; D002850:Chromatography, Gel; D004492:Edetic Acid / Q000494:pharmacology; D006632:Histamine / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008214:Lymphocytes / Q000032:analysis*; D008274:Magnesium; D009000:Monocytes / Q000032:analysis*; D011092:Polyethylene Glycols / Q000494:pharmacology; D011968:Receptors, Histamine / Q000032:analysis* / Q000187:drug effects; D013696:Temperature; D013997:Time Factors
chemical_list: D011968:Receptors, Histamine; D011092:Polyethylene Glycols; D006632:Histamine; D004492:Edetic Acid; D008274:Magnesium; D002118:Calcium