• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Molecular Biology >Locating the thapsigargin-binding site on Ca2+-ATPase by cryoelectron microscopy
【24h】

Locating the thapsigargin-binding site on Ca2+-ATPase by cryoelectron microscopy

机译：冷冻电子显微镜下的毒胡萝卜素结合位点在Ca2 + -ATPase上的定位

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Thapsigargin (TG) is a potent inhibitor of Ca2+-ATPase from sarcoplasmic and endoplasmic reticula. Previous enzymatic studies have concluded that Ca2+-ATPase is locked in a dead-end complex upon binding TG with an affinity of <1 nhl and that this complex closely resembles the E-2 enzymatic state. We have studied the structural effects of TG binding by cryoelectron microscopy of tubular crystals, which have previously been shown to comprise Ca2+-ATPase molecules in the E., conformation. In particular, we have compared 3D reconstructions of Ca2+-ATPase in the absence and presence of either TG or its dansylated derivative. The overall molecular shape of Ca2+-ATPase in the reconstructions is very similar, demonstrating that the TG/Ca2+-ATPase complex does indeed physically resemble the E-2 conformation, in contrast to massive domain movements that appear to be induced by Ca2+ binding. Difference maps reveal a consistent difference on the lumenal side of the membrane, which we conclude corresponds to the thapsigargin-binding site. Modeling the atomic structure for Ca2+-ATPase into our density maps reveals that this binding site is composed of the loops bet been transmembrane segments M3/M4 and M7/M8. indirect effects are proposed to explain the effects of the S3 stalk segment on thapsigargin affinity as well as thapsigargin-induced changes in ATP affinity. Indeed, a second difference density was observed at the decavanadate-binding site within the three cytoplasmic domains, which we believe reflects an altered affinity as a result of the long-range conformational coupling that drives the reaction cycle of this family of ATP-dependent ion pumps. <(c)> 2001 Academic Press. [References: 36]
机译：Thapsigargin（TG）是来自肌浆网和内质网的Ca2 + -ATPase的有效抑制剂。先前的酶学研究得出的结论是，在以小于1 nhl的亲和力结合TG时，Ca2 + -ATPase被锁定在一个末端复合物中，并且该复合物非常类似于E-2酶促状态。我们已经通过低温电子显微镜对管状晶体进行了研究，研究了TG结合的结构效应，该晶体先前已显示在大肠杆菌构象中包含Ca2 + -ATPase分子。特别是，我们比较了在不存在或存在TG或其丹酰化衍生物的情况下Ca2 + -ATPase的3D重建。在重建中，Ca2 + -ATPase的整体分子形状非常相似，这表明TG / Ca2 + -ATPase复合物确实确实在物理上类似于E-2构象，这与似乎由Ca2 +结合诱导的大量结构域运动形成对比。差异图揭示了膜腔侧的一致差异，我们得出的结论是毒胡萝卜素结合位点。将Ca2 + -ATPase的原子结构建模到我们的密度图中，发现该结合位点由跨膜片段M3 / M4和M7 / M8之间的环组成。提出了间接作用来解释S3茎段对毒胡萝卜素亲和力以及毒胡萝卜素诱导的ATP亲和力变化的影响。确实，在三个胞质结构域的十钒酸盐结合位点观察到第二个差异密度，我们认为这反映了由于长距离构象偶联导致亲和力改变，该构象偶联驱动该ATP依赖离子家族的反应周期泵。 <（c）> 2001年学术出版社。 [参考：36]

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号