MECHANOSENSORY CALCIUM-SELECTIVE CATION CHANNELS IN EPIDERMAL-CELLS
MECHANOSENSORY CALCIUM-SELECTIVE CATION CHANNELS IN EPIDERMAL-CELLS
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DOI：
10.1111/j.1365-313x.1993.tb00013.x
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发表时间：
1993-01-01
期刊：
影响因子：
7.2
通讯作者：
PICKARD, BG
中科院分区：
文献类型：
--
作者：
DING, JP;PICKARD, BG
本文探讨了张力激活的表皮钙离子选择性阳离子通道复合物的性质和可能的功能。多达八个或九个链接的或等效的电导单元或共通道可以一起打开。共通道四联体和五联体的开放时间往往相对较长，在离体质膜的胞质面有毫摩尔Mg 2+（但没有毫摩尔Ca 2+）。对张力的敏感性受跨膜电压和温度调节。在某些情况下，通道活动以有节奏的脉冲同步。某些镧系元素和一种干扰细胞生长素的除草剂在低浓度时会抑制向重力性受体作用于通道系统。具体而言，乙基-N-苯基氨基甲酸酯促进微摩尔水平的张力依赖性活性。在中等吸力下，在膜的细胞外表面以约0.5 μ M提供的Gd 3+促进几秒钟，但随后可能变得抑制。1-2 μ M的提供会更有力地促进并随后抑制（通常是突然且完全的），而在高水平时会立即抑制。La 3+是一种不良的向重力性抑制剂，其作用类似，但更为缓慢，并且仅在更高的浓度下起作用。这些特性，特别是这些对调节的敏感性，表明在体内机械敏感通道必须是机械感觉和机械调节的。它可以用来抵消在膨压变化和细胞膨胀过程中在完整的壁-膜-细胞骨架系统中产生的剪切力，以及转换重力、触摸和弯曲引起的应力。就这种转导受电压和温度调节而言，只要壁-膜-细胞骨架系统经历机械应力，通道也将是这些模态的传感器。
This paper explores the properties and likely functions of an epidermal Ca2+ -selective cation channel complex activated by tension. As many as eight or nine linked or linkable equivalent conductance units or co-channels can open together. Open time for co-channel quadruplets and quintuplets tends to be relatively long with millimolar Mg2+ (but not millimolar Ca2+ ) at the cytosolic face of excised plasma membrane. Sensitivity to tension is regulated by transmembrane voltage and temperature. Under some circumstances channel activity is synchronized in rhythmic pulses. Certain lanthanides and a cytoskeleton-disturbing herbicide that inhibit gravitropic reception act on the channel system at low concentrations. Specifically, ethyl-N-phenylcarbamate promotes tension-dependent activity at micromolar levels. With moderate suction, Gd3+ provided at about 0.5 muM at the extracellular face of the membrane promotes for several seconds but may then become inhibitory. Provision at 1-2 muM promotes and subsequently inhibits more vigorously (often abruptly and totally), and at high levels inhibits immediately. La3+, a poor gravitropic inhibitor, acts similarly but much more gradually and only at much higher concentrations. These properties, particularly these susceptibilities to modulation, indicate that in vivo the mechanosensitive channel must be mechanosensory and mechanoregulatory. It could serve to transduce the shear forces generated in the integrated wall-membrane-cytoskeleton system during turgor changes and cell expansion as well as transducing the stresses induced by gravity, touch and flexure. In so far as such transduction is modulated by voltage and temperature, the channels would also be sensors for these modalities as long as the wall-membrane-cytoskeleton system experiences mechanical stress.