Lipid matters: nicotinic acetylcholine receptor-lipid interactions (Review)
Lipid matters: nicotinic acetylcholine receptor-lipid interactions (Review)
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DOI：
10.1080/09687680210166226
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发表时间：
2002-10-01
影响因子：
--
通讯作者：
Barrantes, FJ
中科院分区：
文献类型：
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作者：
Barrantes, FJ
配体门控离子通道介导响应内源性神经递质的快速细胞间通讯。烟碱乙酰胆碱受体（AChR）是这些膜蛋白超家族中的原型分子。早期的电子自旋共振研究发现了与AChR直接接触的脂质部分，其旋转动力学比散装脂质慢50倍。这乙酰胆碱受体-邻近的脂质区域已被假定为是一个可能的网站的受体功能的脂质调节。利用Laurdan荧光光谱研究了AChR-邻位脂质的溶剂偶极（主要是水）的极性和分子动力学，并引入Forster型共振能量转移（FRET）来表征受体相关的脂质微环境。FRET使人们能够区分散装脂质和乙酰胆碱受体-邻位脂质。后者是在一个液体有序相，并表现出更高程度的秩序比散装双层脂质。由脂肪酸、磷脂和胆固醇诱导的FRET效率的变化也导致了这些脂质在AChR蛋白上的离散位点的鉴定。在用荧光方法描绘AChR膜包埋结构域的拓扑结构后，用定点突变和膜片钳记录探索了类固醇的位点，发现在α M1、α M4、γ-M1和γ-N4跨膜区中芘标记的Cys残基位于浅的位置。对于M4片段，这与典型的线性α-螺旋一致;对于M1，有必要假设大量的非螺旋结构和/或扭结，以合理化Cys残基的浅位置。Thr（422）突变，一个在α M4中靠近细胞外膜半层的残基，影响AChR功能的类固醇调节，表明其参与类固醇-AChR相互作用。
Ligand-gated ion channels mediate fast intercellular communication in response to endogenous neurotransmitters. The nicotinic acetylcholine receptor (AChR) is the archetype molecule in the superfamily of these membrane proteins. Early electron spin resonance studies led to the discovery of a lipid fraction in direct contact with the AChR, with rotational dynamics 50-fold slower than those of the bulk lipids. This AChR-vicinal lipid region has since been postulated to be a possible site of lipid modulation of receptor function. The polarity and molecular dynamics of solvent dipoles-mainly water-of AChR-vicinal lipids in the membrane have been studied with Laurdan extrinsic fluorescence, and Forster-type resonance energy transfer (FRET) was introduced to characterize the receptor-associated lipid microenvironment. FRET enabled one to discriminate between the bulk lipid and the AChR-vicinal lipid. The latter is in a liquid-ordered phase and exhibits a higher degree of order than the bulk bilayer lipid. Changes in FRET efficiency induced by fatty acids, phospholipids and cholesterol also led to the identification of discrete sites for these lipids on the AChR protein. After delineating the topography of the AChR membrane-embedded domains with fluorescence methods, sites for steroids are being explored with site-directed mutagenesis and patch-clamp recording, Pyrene-labelled Cys residues in alphaM1, alphaM4, gamma-M1 and gammaN4 transmembrane regions were found to lie in a shallow position. For M4 segments, this is in agreement with a canonical linear alpha-helix; for M1, it is necessary to postulate a substantial amount of non-helical structure, and/or of kinks, to rationalize the shallow location of Cys residues. Mutations of Thr(422), a residue close to the extracellular-facing membrane hemilayer in alphaM4, affect the steroid modulation of AChR function, suggesting its involvement in steroid-AChR interactions.