The effects of cholesterol on the nicotinic acetylcholine receptor : an update

Abstract: The pentameric ligand-gated ion channels (pLGIC) constitute a superfamily of neurotransmitter receptors characterized by decoding the neurotransmitter signal into a selective and rapid ion permeation process in the target cell. The lipid environment in which these receptor proteins are embedded plays an important role in modulating their topography and function. This occurs at multiple levels, including receptor trafficking, sorting, distribution and residence lifetime at the cell surface, internalization, and recycling. Cholesterol is a major player in these equilibria, via non-selective physical mechanisms operating on the bulk bilayer and through direct binding to the receptor proteins, the latter resulting in more specific influences on function. This review discusses these subjects using the crosstalk between the paradigm pLGIC, the nicotinic acetylcholine receptor, and its lipid milieu, to illustrate the influence of cholesterol on receptor structural and functional properties. The mutual interaction of the two partners is discussed at various levels of organization, from the more general influences on the lipid phase to the more intimate relationship of the sterol with the annular and nonannular sites on the receptor