Divalent cations in lipid membranes

Divalent cations, primarily calcium (Ca2+) and magnesium (Mg2+), are essential inorganic components that interact with the anionic headgroups of phospholipids within biological membranes [1]. These ions serve to neutralize the negative surface charge of the membrane, thereby reducing electrostatic repulsion between lipid molecules and promoting tighter packing and structural stability [2]. This interaction is crucial for biological processes such as membrane fusion, vesicle trafficking, and the regulation of membrane-bound enzyme activities [3]. In the context of pharmacology, the displacement of these cations from the bacterial outer membrane by polycationic antibiotics like polymyxins is a key mechanism for disrupting membrane integrity in Gram-negative bacteria [4]. Although not a single protein receptor, the divalent cation-lipid complex represents a critical physiological environment that influences drug-membrane interactions and cellular signaling [5]. References: [1] Alberts B, et al. Molecular Biology of the Cell. [2] Papahadjopoulos D. (1978). Calcium-induced phase changes and fusion in natural and model membranes. [3] McLaughlin S, et al. (1981). Adsorption of divalent cations to bilayer membranes. [4] Trimble MJ, et al. (2006). Polymyxin: a new hope in the fight against multi-drug resistant Gram-negative bacteria. [5] Jacobson K, Papahadjopoulos D. (1975). Phase transitions and phase separations in phospholipid membranes induced by changes in temperature, pH, and concentration of divalent cations.

Other names

Divalent metal ionsMembrane-associated divalent cationsCa2+/Mg2+ membrane complex

Competitive displacement of cations from anionic lipid sites (e.g., LPS) to disrupt membrane integrity; ionophore-mediated transport across the hydrophobic core.