表面受体首先识别胞外信号的刺激(化学配体的结合或光信号 等物理刺激)使其构象发生改变,并通过自身或与其它蛋白的 相互作用把信号跨膜传导到膜的胞浆面或膜下邻近胞浆处的效 应器分子,产生新的放大信号,启动细胞反应或者通过一系列 级联反应最后产生生理效应。总的说来受体的运作机制包括配 体一受体,受体一效应器这两个紧密相关的环节,其中配体与 受体的相互作用是首要的环节,这是一个与酶动力学类似的平 衡过程。在不同的学说的基础上,建立和发展了许多数学模型 以定量分析配体与受体相互作用的动力学。除了经典的并沿用 至今的cark的“占有学说”( occupation theory),早期还有速率学 说( rate theory)、变构学说( allosteric theory),对占有学说作修正 和补充。二十多年来,随着受体研究的深入,又出现了“7TM 受体”模型和“立体三元复合模型
表面受体首先识别胞外信号的刺激（化学配体的结合或光信号 等物理刺激）使其构象发生改变，并通过自身或与其它蛋白的 相互作用把信号跨膜传导到膜的胞浆面或膜下邻近胞浆处的效 应器分子，产生新的放大信号，启动细胞反应或者通过一系列 级联反应最后产生生理效应。总的说来受体的运作机制包括配 体－受体，受体－效应器这两个紧密相关的环节，其中配体与 受体的相互作用是首要的环节，这是一个与酶动力学类似的平 衡过程。在不同的学说的基础上，建立和发展了许多数学模型 以定量分析配体与受体相互作用的动力学。除了经典的并沿用 至今的clark的“占有学说”(occupation theory)，早期还有速率学 说(rate theory)、变构学说(allosteric theory)，对占有学说作修正 和补充。二十多年来，随着受体研究的深入，又出现了“7TM 受体”模型和“立体三元复合模型”
2). Cell-surface receptors specially binding the soluble hydrophilic ligands or insoluble ligands The stimulation arising from these contacts may be converted(transduced) by the cell membrane into intracellular signals that are transmitted along diverse pathways to trigger the cell s response. There are also cases where ligands(such as neurotransmitter, Ach) binding to cell-surface-receptors evoke their response (Such as opening an ion channel that lies within the receptor itself) directly without having to initiate a signal inside the cell
2) Cell-surface receptors specially binding the soluble, hydrophilic ligands or insoluble ligands The stimulation arising from these contacts may be converted (transduced) by the cell membrane into intracellular signals that are transmitted along diverse pathways to trigger the cell’s response. There are also cases where ligands (such as neurotransmitter, Ach) binding to cell-surface-receptors evoke their response (such as opening an ion channel that lies within the receptor itself) directly without having to initiate a signal inside the cell
RESTING CTIVATE NERVE TERMINAL RVE TERMI crve nerve terminal VOLTAGE- GATE synaptic neurotransmitter leased (chemical postsynaptic ACTIVATED ACTIVE neurotransmitter neurotransmitter in synapte clen
(1)Receptors inside the cells Receptors inside the cells for sufficiently small and hydrophobic signaling molecules, such as steroids retinoids, which can diffuse across the plasma membrane and interacting with a receptor protein inside the cell, turning it into an active transcriptional factor, or such as NO, dissolved gas molecules which passes also through the plasma membrane and binds to some enzymes or other proteins and stimulates them, resulting in further cascade reactions
(1) Receptors inside the cells Receptors inside the cells for sufficiently small and hydrophobic signaling molecules, such as steroids, retinoids, which can diffuse across the plasma membrane and interacting with a receptor protein inside the cell, turning it into an active transcriptional factor, or such as NO, dissolved gas molecules which passes also through the plasma membrane and binds to some enzymes or other proteins and stimulates them, resulting in further cascade reactions
Figure 13.2 Structure of steroid hormones, thy- roid hormone, vitamin D, and retinoic acid The steroids include th sex hormones(testosterone, estrogen, and progesterone), glucocorticoids, and mineralocorticoids Testosterone Estradiol Progesteron NN-C-CH coo Cortis Aldosterone Thyroid hormone CH, Vitamin D3 Retinoic acid Figure 13.3