Mio Kazuhiro, Ogura Toshihiko, Yamamoto Tomomi, Hiroaki Yoko, Fujiyoshi Yoshinori, Kubo Yoshihiro, Sato Chikara
Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology, Umezono 1-1-4, Tsukuba, Ibaraki 305-8568, Japan.
Structure. 2009 Feb 13;17(2):266-75. doi: 10.1016/j.str.2008.12.007.
In response to the intercellular messenger ATP, P2X receptors transfer various sensory information, including pain. Here we have reconstructed the structure of the P2X(2) receptor at 15 A resolution from more than 90,000 particle images, taken with a cryo-electron microscope equipped with a helium-cooled stage. This three-dimensional depiction, presumably in a closed state, revealed an elongated vase-shaped structure 202 A in height and 160 A in major diameter. The extracellular and transmembrane domains present a two-layered structure, in which a sparse outer layer surrounds a pore-forming inner density. The decreased diameter of a putative ion-conducting pathway at the middle of the membrane was considered to be the narrowest part of the pore, which has been predicted from electrophysiological studies. The sparse, extended structure of the P2X(2) receptor indicates a loose assembly of subunits, which could be a basis for the activation-dependent pore dilation of P2X receptors.
作为对细胞间信使三磷酸腺苷（ATP）的响应，P2X受体传递包括疼痛在内的各种感觉信息。在此，我们利用配备氦冷却台的低温电子显微镜，从90000多张颗粒图像中重建了分辨率为15埃的P2X(2)受体结构。这个三维描绘大概处于封闭状态，揭示了一个高度为202埃、长径为160埃的细长花瓶状结构。细胞外和跨膜结构域呈现出两层结构，其中稀疏的外层围绕着形成孔道的内部致密结构。膜中部假定的离子传导途径直径减小被认为是孔道最窄的部分，这是根据电生理研究预测出来的。P2X(2)受体稀疏、延伸的结构表明亚基组装松散，这可能是P2X受体激活依赖性孔道扩张的基础。
