GAP JUNCTION

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 缝隙连接是在细胞-细胞对位区发现的质膜特化。 它们包含数万到数千个通道，允许1的分子运动 相邻细胞之间的Kda或更小。间隙连接通道由以下构件构建 连接蛋白(Cx)家族，大小从~23 kDa到~62 kDa不等，尽管 研究最多的连接蛋白是Cx26(26 KDa)、Cx32(32 KDa)和Cx43(43 KDa)。一个缺口 连接通道由两个连接蛋白六聚体(半通道)组成，分别来自 相互作用的细胞，背靠背堆叠在一起。单粒子重建被用来 合成更完整的连接蛋白50(CX50)的三级结构 半条腿。CX50缝隙连接在晶状体和功能障碍中发挥重要作用 CX50突变错误会导致先天性白内障。GAP的结构研究 用电子或X射线结晶学方法得到的结通道是原子的 或Cx26和C端截短的Cx43的近原子分辨结构。僵硬的 跨膜和胞外区被分解，但灵活的细胞质环 和C-末端由于无序或截断而没有得到充分的可视化。 在大于~40 kDa的连接蛋白中，这些细胞质结构域，特别是C- 末端通常含有与N末端一样多的氨基酸、跨膜和 细胞外域结合在一起。这些胞质结构域含有重要的激酶。 PDZ结构域蛋白(如ZO-1)、微管蛋白、Debrin的调节结构域和结合位点 (一种肌动蛋白结合蛋白)，可能还有钙粘附素或连环蛋白。因此， 晶体结构缺少结构的重要部分。我们已经做出了 玻璃化冷冻-EM方法成像CX50蛋白及其重建的研究进展 单粒子法。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Gap junctions are plasma membrane specializations found at cell-cell appositional areas. They contain tens to thousands of channels that allow the movement of molecules of 1 kDa or less between neighboring cells. Gap junction channels are built from members of the connexin (Cx) protein family, ranging in size from ~23 kDa to ~62 kDa, although the most studied connexins are Cx26 (26 kDa), Cx32 (32 kDa) and Cx43 (43 kDa). A gap junction channel consists of two connexin hexamers (hemichannels), one from each of the interacting cells, stacked back-to-back. Single particle reconstruction is being used to synthesize a more complete view of the tertiary structure of Connexin50 (Cx50) hemichannels. Cx50 gap junctions play important roles in the lens and dysfunction or mistrafficking of Cx50 mutants results in congenital cataracts. Structural studies of gap junction channels using electron or X-ray crystallographic methods have obtained atomic or near atomic resolution structures for Cx26 and a C-terminal truncated Cx43. The rigid transmembrane and extracellular domains are resolved, but the flexible cytoplasmic loop and C-terminus have not been adequately visualized either due to disorder or truncation. In connexins larger than ~40 kDa, these cytoplasmic domains, particularly the C- terminus, often contain as many amino acids as the N-terminus, transmembrane and extracellular domains combined. These cytoplasmic domains contain important kinase regulatory domains and binding sites for PDZ domain proteins (e.g. ZO-1), tubulin, debrin (an actin-binding protein) and possibly cadherins or ¿-catenin. Therefore, the crystallographic structures are missing important parts of the structure. We have made advances in imaging Cx50 pannexons using vitrified cryo-EM methods and reconstruction with single particles methods.