第二节受体感受信号 Section 2 perception of signals by receptors 1.受体 启动信号传递,信号首先要被受体识别。受体是指在位于细胞质膜上或细胞质内 能识别胞内或胞外信号物质,并引发胞内变化的特殊分子。大多数已知的受体镶 嵌于质膜上,有些存在于细胞质和其他细胞器上(图7-3)。大多数已知的受体是 蛋白质。在动物细胞中至少已发现三种类型的受体,分别是:G蛋白结合受体, 类受体蛋白激酶和离子通道受体。这三类受体是否都存在于植物细胞中还不清 楚。大多数受体是蛋白质,受体一般应符合以下几个特点:1.配体与受体的结合 是特异的,配体只与其自身受体的特异位点结合。2.受体与配体有较高的亲和 力。这种结合必须有足够的强度并维持一定的时间保证下游反应的激活。3.受体 与配体的结合是可逆的,使得系统能根据配体浓度的变化做出反应 Receptors To initiate transduction, a signal must first be sensed by a receptor. A receptor is a molecule found on the cell surface or inside of a cell, which receives sp ecific signals from neighboring cells or the environment, and trigger intracellula r changes. Most known receptorsare embedded in the plasma membrane, some are located in the cytosol or other cellular compartments (figure 7-3). At lea st three different classes of cell surface receptors have been detected in animal S, which are G-protein-linked receptor; receptor-like protein kinases and ion cha nnels; but whether all three exist in plants is still uncertain. Generally, the foll owing set of criteria need to be fulfilled to identify a molecule as a receptor (1)The binding of ligands to their receptor should be specific, ligands only bi ceptor should be of relatively high affinity, and of sufficient strength so that th e associated downstream processes can be activated. (3) The binding of ligands to their receptor should be reversible, allowing the system to respond to chan Categories of signals 2.信号的种类 在整个生命周期中,植物和植物细胞必须不断地对各种信号作出反应并通过信号 传递来改变其生理,形态和发育。这些将信息传递给植物的信号根据其来源可分 为胞内和胞外信号;根据其性质可分为物理信号和化学信号。物理信号包括光 重力,膨压,机械张力,风,热,冷,冻。化学信号包括矿质营养,有机代谢产 物,生长调节物和激素。植物细胞感受到的信号种类和数量每时每刻都不同,有 些信号分子通过木质部或韧皮部传递,这些信号能以较快的速度传递以较大量 地积累。细胞感受到物理或化学信号后,将信息从胞外传向胞内。 Throughout their life cycle, plants and plant cells continually respond to signals that they use to alter their physiology, morphology, and development. Signals that convey information to plants can be classified into external signals and internal signals based on their origins. Signals can also be grouped into physical signals and chemical signals based on their properties. Physical signals are in the form of light, gravity turgor, mechanical tensions, wind, heat, cold and freezing. Chemical signals include第二节 受体感受信号 Section 2 perception of signals by receptors 1.受体 启动信号传递，信号首先要被受体识别。受体是指在位于细胞质膜上或细胞质内 能识别胞内或胞外信号物质，并引发胞内变化的特殊分子。大多数已知的受体镶 嵌于质膜上，有些存在于细胞质和其他细胞器上(图7-3)。大多数已知的受体是 蛋白质。在动物细胞中至少已发现三种类型的受体，分别是: G蛋白结合受体， 类受体蛋白激酶和离子通道受体。这三类受体是否都存在于植物细胞中还不清 楚。大多数受体是蛋白质, 受体一般应符合以下几个特点：1.配体与受体的结合 是特异的, 配体只与其自身受体的特异位点结合。2.受体与配体有较高的亲和 力。这种结合必须有足够的强度并维持一定的时间保证下游反应的激活。3.受体 与配体的结合是可逆的,使得系统能根据配体浓度的变化做出反应。 Receptors To initiate transduction, a signal must first be sensed by a receptor. A receptor is a molecule found on the cell surface or inside of a cell, which receives sp ecific signals from neighboring cells or the environment, and trigger intracellula r changes. Most known receptorsare embedded in the plasma membrane, some are located in the cytosol or other cellular compartments (figure 7-3). At lea st three different classes of cell surface receptors have been detected in animal s, which are G-protein-linked receptor; receptor-like protein kinases and ion cha nnels; but whether all three exist in plants is still uncertain. Generally, the foll owing set of criteria need to be fulfilled to identify a molecule as a receptor. (1) The binding of ligands to their receptor should be specific, ligands only bi nd to the specific site of their receptors. (2) The binding of ligands to their re ceptor should be of relatively high affinity, and of sufficient strength so that th e associated downstream processes can be activated. (3) The binding of ligands to their receptor should be reversible, allowing the system to respond to chan ges in ligand concentration, Categories of signals 2. 信号的种类 在整个生命周期中，植物和植物细胞必须不断地对各种信号作出反应并通过信号 传递来改变其生理，形态和发育。这些将信息传递给植物的信号根据其来源可分 为胞内和胞外信号； 根据其性质可分为物理信号和化学信号。物理信号包括光， 重力，膨压，机械张力，风，热，冷，冻。化学信号包括矿质营养，有机代谢产 物，生长调节物和激素。植物细胞感受到的信号种类和数量每时每刻都不同，有 些信号分子通过木质部或韧皮部传递， 这些信号能以较快的速度传递以较大量 地积累。细胞感受到物理或化学信号后，将信息从胞外传向胞内。 Throughout their life cycle, plants and plant cells continually respond to signals that they use to alter their physiology, morphology, and development. Signals that convey information to plants can be classified into external signals and internal signals based on their origins. Signals can also be grouped into physical signals and chemical signals based on their properties. Physical signals are in the form of light, gravity, turgor, mechanical tensions, wind, heat, cold and freezing. Chemical signals include