How does the local environment alter the mechanism of two ligand-gated ion channels: oocytes vs HEKs

Abstract

There is increasing interest in determining how lipids and the local environment modulate the function of pentameric ligand-gated ion channels (pLGICs), key mammalian signalling proteins. The action of the Torpedo nicotinic acetylcholine receptor (nAChR), a model pLGIC, can be controlled by a combination of bilayer composition and thickness. However the question of how lipids and the local environment affect mammalian pLGICs is almost entirely open. We have probed the context dependency of cationic mammalian pLGICs by assaying them in both HEK293 cells and Xenopus oocytes, using fluorescence, two-electrode voltage clamp, and single-cell patch clamp electrophysiology to investigate the effects of mutations in the outermost lipid-facing transmembrane helix (M4).