Plasmalemmal ATPase calcium pump localizes to inner and outer hair bundles.
Plasmalemmal ATPase calcium pump localizes to inner and outer hair bundles.
复制标题
质膜 ATP 酶钙泵定位于内部和外部毛束。
DOI：
10.1016/s0306-4522(97)00035-3
复制
发表时间：
1997
期刊：
影响因子：
3.3
通讯作者：
Hillman,DE
中科院分区：
文献类型：
--
作者：
Apicella,S;Chen,S;Bing,R;Penniston,JT;Llinas,R;Hillman,DE
最近的研究表明，钙离子内流的毛细胞静纤毛的尖端在力学转导。这些离子必须从胞质溶胶被泵入细胞外空间或内质被膜，或者通过与特定蛋白质结合而被隔离。用单克隆抗体分析了大鼠Corti器的质膜钙泵（ATP酶型）。反应是特别高的较长的静纤毛的尖端，并发现沿着轴。内毛细胞静纤毛的反应性远低于外毛细胞。内毛细胞胞体的细胞膜呈线状排列，外毛细胞胞质中有较高的反应性。支持细胞没有反应。超微结构观察证实质膜钙泵定位于静纤毛和沿着内淋巴表面的受体细胞。反应产物排列在静纤毛的质膜上，呈密集点状。静纤毛远端反应点较多，且数量向睫状体基部逐渐减少。表皮切迹上方的内淋巴质膜反应性特别强。在静纤毛的尖端处比基部处更强烈的泵反应性的发现与以下假设一致：在转导期间，钙离子进入静纤毛，远端，并且ATP酶质膜钙泵快速地将这些离子挤出到细胞外空间。
Recent studies demonstrate calcium ion influx at the tips of hair cell stereocilia during mechano-transduction. These ions must be either pumped from the cytosol into the extracellular space or endoplasmic envelope, or else sequestered by binding to specific proteins. A plasma membrane calcium pump (ATPase-type) was analysed in whole-mounts of rat organ of Corti using a monoclonal antibody to a large cytoplasmic loop of this protein. The reactivity was particularly high on the tips of longer stereocilia and was found along the shafts. Inner hair cell stereocilia had much less reactivity than outer hair cells. The reactivity lined the plasma membrane of inner hair cell bodies while a higher reactivity appeared in the cytoplasm of outer hair cells. Supporting cells were unreactive. Ultrastructural examination confirmed the plasma membrane calcium pump location on stereocilia and along the endolymph surface of receptor cells. Reaction product lined the plasma membrane of stereocilia as intense puncta. More reactive puncta occurred near the distal ends of stereocilia and the number decreased toward the ciliary base. The endolymph plasma membrane over the cuticular notch was especially reactive. The finding of more intense pump reactivity at the tips of stereocilia than the base is consistent with the hypothesis that during transduction, calcium ions enter stereocilia, distally, and the ATPase plasma membrane calcium pump rapidly extrudes these ions to the extracellular space.