INFLUENCE OF PROTEIN/LIPID INTERACTIONS ON SIGNAL TRANSDUCTION

G蛋白偶联受体是普遍存在的信号成分 转导系统 该项目包括评估 多不饱和磷脂在调节G蛋白偶联信号中的作用 转导和阐明的作用机制，乙醇在 这些系统。 在这些研究中，视觉传导通路， 原型G蛋白偶联系统，被用作模型系统。 酒精、麻醉剂和脂质成分对： 后视紫红质II（MII），G蛋白， 视紫红质活化型; MII/G蛋白复合物形成;速率 G蛋白激活; cGMP磷酸二酯酶激活; 正在研究G蛋白的GT酶活性。 我们已经证明 短链醇，如乙醇，促进MII的形成，而 较长链的醇如癸醇是抑制性的。 中间 长链醇显示出从兴奋性到抑制性的平滑过渡。 所观察到的效应的大小取决于磷脂 酰基链组成。 乙醇，酰基链组成， 和胆固醇与磷脂酰的变化密切相关 链堆积自由体积，其特征在于时间分辨 膜探针的荧光各向异性行为， 二苯基己三烯 我们的结果强烈支持脂质介导的 醇在调节G蛋白活化中的作用机制 蛋白偶联受体 我们的观察最好用一本小说来解释 脂质包装模型在这个实验室，其中存在 多不饱和酰基链，在混合的饱和-不饱和和 二多不饱和酰基链磷脂，导致形成 膜表面的侧域或簇。 许多 已发表的研究表明， 乙醇剂量以产生可观察到的反应。 我们已经证明 增加样品溶液的渗透压，以便更好地 模拟细胞质条件，增加乙醇的功效，从而 减少乙醇需求以达到观察到的相同反应 在标准缓冲溶液中。

G protein-coupled receptors are ubiquitous components of signal transduction systems. This project includes an assessment of the role of polyunsaturated phospholipids in modulating G protein-coupled signal transduction and an elucidation of the mechanism of action of ethanol in these systems. In these studies, the visual transduction pathway, a prototypical G protein-coupled system, is being used as a model system. The effect of alcohols, anesthetics, and lipid composition on: the kinetics and extent of formation of metarhodopsin II (MII), the G protein activating form of rhodopsin; MII/G protein complex formation; the rate of G protein activation; cGMP phosphodiesterase activation; and the GTPase activity of the G protein are being studied. We have shown that short chain alcohols, such as ethanol, promote MII formation, while longer chain alcohols, such as decanol, are inhibitory. Intermediate length alcohols show a smooth transition from excitatory to inhibitory. The magnitude of the observed effects are dependent on the phospholipid acyl chain composition. The effects of ethanol, acyl chain composition, and cholesterol are well correlated with changes in phospholipid acyl chain packing free volume, as characterized by the time-resolved fluorescence anisotropy behavior of the membrane probe, diphenylhexatriene. Our results strongly support a lipid-mediated mechanism of action for alcohols in modulating the activation of a G protein-coupled receptor. Our observations are best explained by a novel lipid packing model developed in this laboratory, in which the presence of polyunsaturated acyl chains, in mixed saturated-unsaturated and dipolyunsaturated acyl chain phospholipids, leads to the formation of lateral domains or clusters in the surface of the membrane. Many published studies demonstrate a requirement for higher than physiological ethanol doses to produce an observable response. We have shown that increasing the osmolality of the sample solution, so as to better simulate cytosolic conditions, increases the efficacy of ethanol, thereby reducing the ethanol requirement to achieve the same response observed in standard buffer solution.