Transbilayer asymmetry and sphingomyelin composition modulate the preferential membrane partitioning of the nicotinic acetylcholine receptor in Lo domains

• Published in: Archives of biochemistry and biophysics Vol. 591; pp. 76 - 86
• Main Authors: Perillo, Vanesa L., Peñalva, Daniel A., Vitale, Alejandro J., Barrantes, Francisco J., Antollini, Silvia S.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-02-2016
• Subjects: Binding Sites; Fluorescence; Lipid Bilayers - chemistry; Lipid raft; Liposomes; Membrane Fluidity; Membrane Microdomains - chemistry; Nicotinic acetylcholine receptors; Protein Binding; Protein Structure, Tertiary; Receptors, Nicotinic - chemistry; Sphingolipids; Sphingomyelins - chemistry; Transbilayer asymmetry; Fluorescence; Lipid raft; Transbilayer asymmetry; Sphingolipids; Liposomes; Nicotinic acetylcholine receptors
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2015.12.003

We have previously shown that the intact nicotinic acetylcholine receptor (AChR) lacks preference for Lo domains when reconstituted in a sphingomyelin (SM), cholesterol (Chol) and POPC (1:1:1) model system (Bermúdez V, Antollini SS, Fernández-Nievas GA, Aveldaño MI, Barrantes FJ. J. Lipid Res. 2010; 51: 2629–2641). Here, we have furthered our studies by characterizing the influence of different lipid host compositions on the distribution of purified AChR reconstituted in two model systems (POPC:Chol, 1:1 and POPC:Chol:SM, 1:1:1), involving a) different SM species (porcine brain SM (bSM), 16:0-SM, 18:0-SM or 24:1-SM); or b) induced transbilayer asymmetry, resulting from enrichment in bSM in the external hemilayer. AChR distribution was evaluated by fluorescence resonance energy transfer efficiency between the AChR intrinsic fluorescence and Laurdan or dehydroergosterol fluorescence, and by analyzing the distribution of AChR in detergent-resistant and detergent-soluble fractions (1% Triton X-100, 4 °C). bSM-induced transbilayer asymmetry or the presence of 16:0-SM and/or 18:0-SM (unlike bSM or 24:1-SM) resulted in the preferential partitioning of AChR in Lo domains, suggesting that the localization of AChR in ordered domains strongly depends on the characteristics of the host lipid membrane, and in particular on the sphingolipid composition and transbilayer asymmetry.
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•16:0-sphingomyelin favors acetylcholine receptor (AChR) in liquid-ordered domains.•18:0-sphingomyelin also favors AChR in liquid-ordered (Lo) domains.•Neither brain nor 24:1 sphingomyelins promote a preference of Lo domains.•Induction of asymmetry in symmetric models promotes AChR preference of Lo domains.•Intrinsic membrane factors modify AChR's preference for localizing in Lo domains.