Formation of Pores in Membranes Asymmetrical in Lipid Composition of Monolayers

Abstract

Plasma membranes perform a barrier function in cells, preventing free exchange between the external environment and the intracellular space. The permeability of the plasma cell membrane can be artificially increased by forming through pores. The outer and inner monolayers of the plasma membranes of cells typically have different lipid compositions. Currently, a theoretical description of the poration of membranes with monolayers symmetrical in lipid composition has been developed. In the present work, we consider the process of pore formation in membranes, whose monolayers have different spontaneous curvatures due to the difference in their lipid composition. In the framework of the theory of lipid membrane elasticity and considering hydrophobic interactions, the dependence of the pore energy on the radius is calculated. It is shown that the dependences of pore energy on radius are qualitatively different in asymmetric and symmetric membranes. The pore energy in the asymmetric membrane differs from the pore energy in the symmetric membrane at any values of the spontaneous curvature of the monolayers of the symmetric membrane. Thus, it is incorrect to predict the course of the pore formation in an asymmetric membrane on the basis of data obtained on symmetric membranes; the asymmetry of lipid composition (spontaneous curvature) of monolayers should be explicitly taken into account.