Calmodulin controls adaptation of mechanoelectrical transduction by hair cells of the bullfrog's sacculus.
Calmodulin controls adaptation of mechanoelectrical transduction by hair cells of the bullfrog's sacculus.
复制标题
钙调蛋白控制牛蛙球囊毛细胞对机械电转导的适应。
DOI：
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发表时间：
1996
影响因子：
11.1
通讯作者：
A. Hudspeth
中科院分区：
文献类型：
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作者：
R. G. Walker;A. Hudspeth
毛细胞顶部的机械敏感的毛束的偏转打开转导通道，其中一些随后在Ca 2+依赖的适应过程中重新闭合。毛束中的肌球蛋白I被认为介导了这种适应;在牛蛙的毛细胞中，相关的同工酶可能是119 kDa的两栖动物肌球蛋白I β。因为这种分子类似于肌球蛋白I的其他形式，我们假设钙调蛋白，一种细胞质Ca 2+受体，调节肌球蛋白的ATP酶活性。我们确定了一个约120 kDa的钙调素结合蛋白，头发束肌球蛋白I的股票被钒酸捕获的尿苷核苷酸的光标记和免疫反应性的单克隆抗体对哺乳动物肌球蛋白I β的属性。为了研究钙调蛋白介导钙依赖性适应的可能性，我们抑制钙调蛋白的作用，并测量了两个不同的测定结果。钙调素拮抗剂增加核苷酸对毛束肌球蛋白I的光标记。此外，当通过记录电极引入毛细胞时，钙调素拮抗剂消除了对持续机械刺激的适应。我们的证据表明，钙调蛋白结合并控制活动的毛束肌球蛋白I，推定的适应电机。
Deflection of the mechanically sensitive hair bundle atop a hair cell opens transduction channels, some of which subsequently reclose during a Ca2+-dependent adaptation process. Myosin I in the hair bundle is thought to mediate this adaptation; in the bullfrog's hair cell, the relevant isozyme may be the 119-kDa amphibian myosin I beta. Because this molecule resembles other forms of myosin I, we hypothesized that calmodulin, a cytoplasmic receptor for Ca2+, regulates the ATPase activity of myosin. We identified an approximately 120-kDa calmodulin-binding protein that shares with hair-bundle myosin I the properties of being photolabeled by vanadate-trapped uridine nucleotides and immunoreactive with a monoclonal antibody raised against mammalian myosin I beta. To investigate the possibility that calmodulin mediates Ca2+-dependent adaptation, we inhibited calmodulin action and measured the results with two distinct assays. Calmodulin antagonists increased photolabeling of hair-bundle myosin I by nucleotides. In addition, when introduced into hair cells through recording electrodes, calmodulin antagonists abolished adaptation to sustained mechanical stimuli. Our evidence indicates that calmodulin binds to and controls the activity of hair-bundle myosin I, the putative adaptation motor.