title: AFM imaging reveals the tetrameric structure of the TRPM8 channel.
abstract: Several members of the transient receptor potential (TRP) channel superfamily have been shown to assemble as tetramers. Here we have determined the subunit stoichiometry of the transient receptor potential M8 (TRPM8) channel using atomic force microscopy (AFM). TRPM8 channels were isolated from transfected cells, and complexes were formed between the channels and antibodies against a V5 epitope tag present on each subunit. The complexes were then subjected to AFM imaging. A frequency distribution of the molecular volumes of antibody decorated channels had a peak at 1305 nm(3), close to the expected size of a TRPM8 tetramer. The frequency distribution of angles between pairs of bound antibodies had two peaks, at 93 degrees and 172 degrees, confirming that the channel assembles as a tetramer. We suggest that this assembly pattern is common to all members of the TRP channel superfamily.
authors.affiliation: Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB21PD, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Stewart
authors.forename: Kinga
authors.initials: K
authors.lastname: Egressy
authors.forename: Annabel
authors.initials: A
authors.lastname: Lim
authors.forename: J Michael
authors.initials: JM
authors.lastname: Edwardson
mesh_terms: D000818:Animals; D002460:Cell Line; D018625:Microscopy, Atomic Force; D011487:Protein Conformation; D055503:Protein Multimerization; D051381:Rats; D050053:TRPM Cation Channels / Q000737:chemistry*
chemical_list: D050053:TRPM Cation Channels; C498947:Trpm8 protein, rat