title: Stimulation of lymphocyte receptor capping by the ionophore monensin.
abstract: The carboxylic ionophore monensin has a biphasic effect on antibody-induced Thy-1 cap formation. At higher concentrations, 5 X 10(-6)-5 X 10(-5) M monesin causes a significant inhibition of receptor capping similar to that previously found with the Ca2+ selective ionophore A23187. At lower concentrations, 5 X 10(-8)-5 X 10(-7) M capping is stimulated. It is concluded that capping at lower ionophore concentrations is a specific response to the ability of monensin to induce a rise in intracellular Na+, which indirectly elevates intracellular Ca2+ activity. This in turn activates the contractile machinery required for the aggregation of surface receptors into capped structures. At higher concentrations monensin acts as a nonspecific detergent, which causes detrimental structural alterations in some of the membrane components involved in the capping process.
mesh_terms: D000818:Animals; D000954:Antigens, Surface; D002460:Cell Line; D005663:Furans / Q000494:pharmacology*; D007152:Immunologic Capping / Q000187:drug effects*; D007476:Ionophores / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects* / Q000276:immunology; D051379:Mice; D008985:Monensin / Q000494:pharmacology*; D011971:Receptors, Immunologic / Q000502:physiology; D018800:Thy-1 Antigens
chemical_list: D000954:Antigens, Surface; D005663:Furans; D007476:Ionophores; D011971:Receptors, Immunologic; D018800:Thy-1 Antigens; D008985:Monensin