# Untangling direct and domain-mediated interactions between nicotinic acetylcholine receptors in DHA-rich membranes

## TL;DR

This study uses molecular dynamics simulations to explore how lipid domains influence nicotinic acetylcholine receptor clustering and lipid preferences in membranes, revealing that DHA-rich domains promote receptor dimerization and affect lipid access.

## Contribution

It provides new insights into the role of lipid domains and DHA in nAChR clustering and membrane organization, using detailed simulation approaches.

## Key findings

- Dimerization of nAChRs is more likely in domain-forming membranes.
- nAChRs preferentially partition into DHA-rich liquid-disordered domains.
- Protein concentration influences lipid boundary composition and access.

## Abstract

At the neuromuscular junction (NMJ), the nicotinic acetylcholine receptor (nAChR) self-associates to give rise to rapid muscle movement. While lipid domains have maintained nAChR aggregates in-vitro, their specific roles in nAChR clustering are currently unknown. In the present study, we carried out coarse-grained molecular dynamics simulations (CG-MD) of 1-4 nAChR molecules in two membrane environments: One mixture containing domain-forming, homoacidic lipids, and a second mixture consisting of heteroacidic lipids. Spontaneous dimerization of nAChRs was up to ten times more likely in domain-forming membranes; however, the effect was not significant in four-protein systems, suggesting that lipid domains are less critical to nAChR oligomerization when protein concentration is higher. With regard to lipid preferences, nAChRs consistently partitioned into liquid-disordered domains occupied by the omega-3 ($\omega$-3) fatty acid, Docosahexaenoic acid (DHA); enrichment of DHA boundary lipids increased with protein concentration, particularly in homoacidic membranes. This result suggests dimer formation blocks access of saturated chains and cholesterol, but not polyunsaturated chains, to boundary lipid sites.