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水通道蛋白是对水专一的通道蛋白,普遍存在于动、植物及微生物中。研究表明高等植物的质膜和液泡膜上存在着丰富的水通道蛋白,其种类繁多,分布广泛,并具有一定的组织特异性。植物水通道蛋白的活性受到严格的调控,其调节方式主要有两种,分别为基因水平的表达调控和翻译后的修饰作用。 相似文献
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水通道蛋白是细胞间和细胞内水分运输的主要通道,其运输和调控对于植物细胞的水分稳态和胁迫响应具有重要作用。本文综述了水通道蛋白运输的分子机制以及结构修饰、门控、膜转运和异源四聚体等调节机制。 相似文献
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肾集合管主细胞管腔膜AQP2水通道蛋白数量受抗利尿激素(ADH)的调节。当血浆ADH为零值时,管腔膜AQP2数量减少,集合管水通透性降低。当血浆ADH水平升高时,管腔膜AQP2数量增加,集合管水通透性升高。 相似文献
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水通道,又称水蛋白,是一系列具有同源性的内在膜蛋白家族成员。它们介导着不同类型细胞膜的跨膜水转运。迄今,已从哺乳动物组织中鉴定出6种水蛋白,除定位于肾集合管上皮细胞的AQP-CD特异地对加压素敏感外,限水和盐适应及某些药物也可影响AQPa的功能和表达。 相似文献
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水通道蛋白 总被引:5,自引:0,他引:5
水通道蛋白 (aquaporin,AQP)是对水专一的通道蛋白 ,普遍存在于动、植物及微生物中。它所介导的自由水快速被动的跨生物膜转运 ,是水进出细胞的主要途径。1 水通道蛋白的发现长期以来 ,普遍认为细胞内外的水分子是以简单的跨膜扩散方式来透过脂双层膜。后来由于在生物物理学研究中发现红细胞及近端肾小管对渗透压改变引起的水的通透性很高 ,很难单纯以弥散来解释。因此 ,一些学者推测水的跨膜转运除了简单扩散外 ,还存在某种特殊的机制 ,并提出了水通道的概念。1988年 ,Agre等在鉴定人类 Rh血型抗原时 ,偶然在红细胞膜上发现了 1种新的 2… 相似文献
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The plant plasma membrane is the the major barrier to water flow between cells and their surroundings. Water movement across roots involves pathways comprising many cells and their walls. There are three possible pathways which water can follow, (i) a trans-cellular pathway, which involves serial movement into and out from radial files of cells, (ii) a symplasmic pathway through the plasmodesmata, which creates a cytoplasmic continuum and (iii) a tortuous, extracellular pathway through the cell walls, the apoplasmic pathway. In each of these pathways water movement across cell membranes occurs at some stage. The possible role of water-channels in membranes is discussed in relation to this movement. The molecular identity of water-channel proteins in plasma membranes of plants has been confirmed but there remain a number of unresolved questions about their role in cell and tissue water relations, their interaction with the lipid components of membranes and the relationship between water movement through membranes by diffusion in the bilayer. 相似文献
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P—gp和细胞容积调节 总被引:1,自引:0,他引:1
本实验用基因阻抑技术阻抑牛眼睫状体非色素上皮(NPE)细胞MDR1基因表达,在激光共聚焦显微镜下检测细胞MDRI基因产物P-gp免疫荧光,研究MDRI基因及P-gp与细胞容积调节的关系。结果表明:NPE细胞表达MDR1基因,存在P-gp蛋白。人反义MDR1特异性阻抑NPE细胞MDR1基因表达,剂量依赖性抑制P-gp免疫荧光(r=0.95,P<0.01),减少P-gp合成,导致细胞容积调节减弱,鼠反义MDR1对NPE细胞MDR1基因表达及容积调节没有影响。结果提示P-gp在细胞容积调节中起重要作用。 相似文献
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我们从白色念珠菌SC5314中分离到两个逆转录转座子样元件Tcal-1和Tcal-2,它们的物理图谱非常相近,两者都能转录成6kb长的RNA,该转录产物的转录受温度调控,25℃条件下的转录产物多于37℃的,Tcal-1元件内侧部分序列或全部序列的缺失引起白色念珠菌形态的改变,这种形态发生的变化与URA3基因的表达有协同作用。 相似文献
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苯酚的生物降解基因组成及其调控机制 总被引:15,自引:1,他引:15
苯酚的生物降解受多组分的降解基因控制,形成邻位和间位等不同的代谢途径.结合部分实验结果,介绍了邻位和间位代谢系统的基因组成及其作用机制等方面的研究进展,讨论了调节基因在苯酚降解菌中的作用和不同因素对苯酚降解的影响. 相似文献
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Thomas Rausch 《Physiologia plantarum》1991,82(1):134-142
The uptake of hexoses in higher plant cells is thought to be catalyzed by an H+ /hexose contrasporter in the plasma membrane. Transport studies with isolated plant vacuoles indicate that, at the tonoplast, a second hexose transporter is located with properties different from the plasma membrane transporter. Recently membrane vesicles of high purity and defined orientation have been used for a more rigorous individual characterization of these two carriers. Concomitantly, a cDNA for the inducible H+ /hexose cotransporter of the green alga Chlorella has been sequenced and shown to exhibit homology to a group of hexose transporters (for facilitated diffusion) of other eukaryotic and prokaryotic organisms. With a probe derived from the Chlorella sequence, the first plant gene for an H+ /hexose contransporter ( Arabidopsis thaliana ) has been isolated, opening the route to molecular studies of structure, function and evolution of the hexose transporters of higher plants. The present review discusses recent work on the kinetic characterization and identification of the higher plant plasma membrane and tonoplast hexose transporters as well as their respective cellular functions. Furthermore, perspectives for future research on the plant hexose transporters are outlined. 相似文献
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Electrolyte leakage of Meloidogyne incognita-infected and healthy tomato roots was compared by conductivity measurements, and by compartmental analysis using ⁸⁶Rb. Conductivity measurements suggested difference in electrolyte loss from healthy and galled roots. On a percentage basis, a greater rate of efflux occurred for healthy plants, but galled roots contain more electrolytes and may show a larger net loss. Compartmental analysis indicated that: (i) the longer half-time for ⁸⁶Rb loss from vacuoles of galled root cells could indicate either a greater vacuolar content or decreased tonoplast permeability, (ii) the shorter half-time for loss ⁸⁶Rb from the cytoplasm of galled root cells could reflect either a reduced cytoplasmic content or an increased plasma membrane permeability, and (iii) in split-root plants, the permeability of the tonoplast and the plasma membrane of cells in nongalled roots is increased by nematode infection on the other half of the root system. Thus, a mechanism for mobilizing minerals to the infection site is proposed. 相似文献