Ionophore A23187 disrupts membrane structure by modifying protein–lipid interactions

Abstract

The physiological function of membrane-bound protein clearly depends on the nature of its neighbouring lipid¹. However, the question of how critical the protein is to the structure and function of membrane lipid has received much less attention. There is some evidence that lipid surrounding membrane protein, ‘boundary lipid’, may be more ordered than continuum lipid². Protein can also alter the enthalpy and temperature of pure lipid-phase transitions³. However, controversy surrounds the question of whether membrane proteins determine long-range aspects of lipid structure or merely perturb their local environments^4,5. Here, we demonstrate that a lipophilic substance, the calcium ionophore, A23187 (Lilly), dramatically disorders the lipid structure of the membrane and that this phenomenon depends on the presence of proteins.