title: Three-dimensional reconstruction using transmission electron microscopy reveals a swollen, bell-shaped structure of transient receptor potential melastatin type 2 cation channel.
abstract: Transient receptor potential melastatin type 2 (TRPM2) is a redox-sensitive, calcium-permeable cation channel activated by various signals, such as adenosine diphosphate ribose (ADPR) acting on the ADPR pyrophosphatase (ADPRase) domain, and cyclic ADPR. Here, we purified the FLAG-tagged tetrameric TRPM2 channel, analyzed it using negatively stained electron microscopy, and reconstructed the three-dimensional structure at 2.8-nm resolution. This multimodal sensor molecule has a bell-like shape of 18 nm in width and 25 nm in height. The overall structure is similar to another multimodal sensor channel, TRP canonical type 3 (TRPC3). In both structures, the small extracellular domain is a dense half-dome, whereas the large cytoplasmic domain has a sparse, double-layered structure with multiple internal cavities. However, a unique square prism protuberance was observed under the cytoplasmic domain of TRPM2. The FLAG epitope, fused at the C terminus of the ADPRase domain, was assigned by the antibody to a position close to the protuberance. This indicates that the agonist-binding ADPRase domain and the ion gate in the transmembrane region are separately located in the molecule.
authors.affiliation: Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-4, Tsukuba, Ibaraki 305-8568, Japan.
authors.forename: Yuusuke
authors.initials: Y
authors.lastname: Maruyama
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Ogura
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Mio
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kiyonaka
authors.forename: Kenta
authors.initials: K
authors.lastname: Kato
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Mori
authors.forename: Chikara
authors.initials: C
authors.lastname: Sato
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000737:chemistry* / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D036563:Cyclic ADP-Ribose / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008854:Microscopy, Electron; D008958:Models, Molecular; D017434:Protein Structure, Tertiary / Q000502:physiology; D011755:Pyrophosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D050052:TRPC Cation Channels / Q000819:agonists / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D050053:TRPM Cation Channels / Q000819:agonists / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human; D036563:Cyclic ADP-Ribose; D000246:Adenosine Diphosphate Ribose; D011755:Pyrophosphatases; C019620:ADPribose pyrophosphatase