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二、通过细胞内受体介导的信号传递 细胞内受体 亲脂 甾类激素和甲状腺素
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Signal transdution mediated by the receptors within cells
A. Nuclear receptors for steroid, retinoic acid类维生素A, vitamin D and thyroid hormones
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甾类激素穿过细胞膜 胞内受体结合进入细胞核 与受体依赖的转录增强子DNA序列相结合 增强相关基因的转录水平 产生相应的蛋白质
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类固醇类激素靶细胞有一万个相应的受体。受体有明显的同源性。
受体在各种细胞中一样,但细胞的反应不同有人认为,有特异性基因调节蛋白,是这种蛋白使不同细胞对相同受体信使复合体有不同的反应。如睾丸素。 睾丸雌性化综合征。(医学332)
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化学信号分子 胞内受体 化学信号分子胞内受体复合物
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甾类激素受体图 基因活化区 与DNA结合区 受体结构 激素结合位点 扩散进入 穿过核膜孔 核膜 复合体 增强子 基因 基因 启动子 抑制蛋白
化学信号分子 基因活化区 与DNA结合区 受体结构 激素结合位点 扩散进入 抑制蛋白 化学信号分子胞内受体复合物 穿过核膜孔 核膜 复合体 增强子 基因 基因 启动子
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信号分子除 蛋白质 肽 氨基酸 脂肪酸 核苷酸 甾类 萜类等。 又发现一些可溶性气体也是信号分子如 NO CO2 当前对细胞因子和NO备受瞩目。NO是一种自由基性质的气体,具有脂溶性,NO在细胞外极不稳定。NO生成细胞是血管内皮细胞。NO是以局部介质发挥作用的。靶细胞内鸟苷酸环化酶的激活是ON发挥作用的主要机制。
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The Nobel Prize in Physiology or Medicine 1998
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The Nobel Assembly at the Karolinska Institute in Stockholm, Sweden, has awarded the Nobel Prize in Physiology or Medicine for 1998 to Robert F Furchgott, Louis J Ignarro and Ferid Murad for their discoveries concerning "the nitric oxide as a signalling molecule in the cardiovascular system".
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Robert F Furchgott, born 1916 Dept
Robert F Furchgott, born 1916 Dept. of Pharmacology, SUNY Health Science Center New York
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Louis J Ignarro, born 1941 Dept
Louis J Ignarro, born 1941 Dept. of Molecular and Medical Pharmacology UCLA School of Medicine Los Angeles
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Ferid Murad, born 1936 Dept. of Integrative Biology Pharmacology and Physiology University of Texas Medical School, Houston
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A New Principle Nitric Oxide, NO, is a short-lived, endogenously produced gas that acts as a signalling molecule in the body. Signal transmission by a gas, produced by one cell, which penetrates membranes and regulates the function of other cells is an entirely new principle for signalling in the human organism.
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Furchgott's sandwich Robert F Furchgott showed that acetylcholine-induced relaxation of blood vessels was dependent on the endothelium内皮. His "sandwich" experiment set the stage for future scientific development. He used two different pieces of the aorta主动脉; one had the endothelial layer intact, in the other it had been removed.
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Ignarro's spectral analysis Louis Ignarro reported that EDRF(内皮细胞松弛因子Undothe1MIn-derived relaxing factor, EDRF) relaxed blood vessels. He also identified EDRF as a molecule by using spectral analysis of hemoglobin血红蛋白.
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When hemoglobin was exposed to EDRF, maximum absorbance moved to a new wave-length; and exposed to NO, exactly the same shift in absorbance occurred! EDRF was identical with NO. A new principle for signalling between human cells was discovered.
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Spectrophotometry,分光光度技术
Hemoglobin (yellow) exposed to endothelial cells that were stimulated to produce EDRF (green)
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Hemoglobin (yellow) directly exposed to NO (green) The shift of absorption curves is identical, hence EDRF is NO
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