Electrophysiology and molecular modeling pinpoint α7 receptor inhibition site

Polyunsaturated free fatty acids negatively modulate the α7 nicotinic acetylcholine receptor through a transmembrane region shared by synthetic positive allosteric modulators, according to a laboratory study combining electrophysiology, coarse-grained molecular-dynamics simulations and mutational analysis. The researchers found that the inhibitory effect varied with the fatty acid’s tail length, degree of unsaturation and head-group polarity, while functional tests implicated an intersubunit site formed by the M3 helix of one receptor subunit and the M1 helix of a neighboring subunit.

The α7 nicotinic acetylcholine receptor is a pentameric ligand-gated ion channel that mediates cholinergic signaling. It has attracted attention because of its roles in neurological disorders and inflammation, which have encouraged the development of synthetic effectors. Those compounds include orthosteric agonists that act on the receptor’s extracellular domain and positive allosteric modulators, known as PAMs, that act in its transmembrane domain. The new research examined endogenous polyunsaturated free fatty acids, or PUFAs, whose ability to modulate α7 receptor function was known but whose site of action had remained unresolved.

Using two-electrode voltage-clamp electrophysiology, Awad and colleagues characterized a series of PUFAs and established structure–activity relationships governing their negative allosteric modulation. The potency of inhibition depended on the length of the hydrophobic tail, the number of double bonds in that tail and the polarity of the head group. These results identified the tested lipids as negative allosteric modulators, or NAMs, and showed that relatively small changes in molecular structure can alter how strongly they suppress receptor activity.

The researchers then combined coarse-grained molecular-dynamics simulations with mutational analysis to search for the molecular basis of that activity. Two candidate locations emerged within the receptor’s transmembrane domain. A major “structural” site lies within the M1 and M4 helices of a single subunit, but mutations and simulations indicated that this location does not contribute to the NAM effect. By contrast, the smaller M3-positive/M1-negative site lies at an interface between adjacent subunits. Mutations in this region strongly impaired NAM activity, making it the principal functional site identified by the study rather than the larger intrachain pocket.

The functionally important intersubunit site overlaps the location associated with synthetic PAMs. This overlap establishes a common structural hotspot at which chemically different modulators can produce opposing effects on the α7 receptor: the tested PUFAs inhibit it, whereas PAMs enhance it. The study did not demonstrate effects in people or establish clinical consequences, and the findings concern the receptor systems and compounds tested. Its principal implication is for the molecular design of α7 receptor modulators and for understanding how endogenous lipid regulation may influence receptor function.

Subject of Research: Molecular mechanisms of polyunsaturated fatty-acid negative allosteric modulation of the α7 nicotinic receptor

Article Title: Pharmacological analysis of negative allosteric modulation of the α7 nicotinic receptor by polyunsaturated free fatty acids

Article References: Awad, N., Sandberg, J., Barilone, N., Lustig, M., Corringer, P.-J., Brannigan, G., & Prevost, M. S. (2026). Pharmacological analysis of negative allosteric modulation of the α7 nicotinic receptor by polyunsaturated free fatty acids. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06498-2

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06498-2

Keywords: α7 nicotinic receptor, polyunsaturated fatty acids, negative allosteric modulators, electrophysiology, molecular dynamics, mutational analysis, transmembrane binding site, ligand-gated ion channel, cholinergic signaling, Pharmacological, analysis, negative