TY - DATA T1 - Amino Acid Residues Contributing to Function of the Heteromeric Insect Olfactory Receptor Complex PY - 2012/03/05 AU - Tatsuro Nakagawa AU - Maurizio Pellegrino AU - Koji Sato AU - Leslie B. Vosshall AU - Kazushige Touhara UR - https://plos.figshare.com/articles/dataset/Amino_Acid_Residues_Contributing_to_Function_of_the_Heteromeric_Insect_Olfactory_Receptor_Complex/128029 DO - 10.1371/journal.pone.0032372 L4 - https://ndownloader.figshare.com/files/344172 L4 - https://ndownloader.figshare.com/files/344225 L4 - https://ndownloader.figshare.com/files/344288 L4 - https://ndownloader.figshare.com/files/344329 KW - amino KW - residues KW - contributing KW - heteromeric KW - olfactory KW - receptor N2 - Olfactory receptors (Ors) convert chemical signals—the binding of odors and pheromones—to electrical signals through the depolarization of olfactory sensory neurons. Vertebrates Ors are G-protein-coupled receptors, stimulated by odors to produce intracellular second messengers that gate ion channels. Insect Ors are a heteromultimeric complex of unknown stoichiometry of two seven transmembrane domain proteins with no sequence similarity to and the opposite membrane topology of G-protein-coupled receptors. The functional insect Or comprises an odor- or pheromone-specific Or subunit and the Orco co-receptor, which is highly conserved in all insect species. The insect Or-Orco complex has been proposed to function as a novel type of ligand-gated nonselective cation channel possibly modulated by G-proteins. However, the Or-Orco proteins lack homology to any known family of ion channel and lack known functional domains. Therefore, the mechanisms by which odors activate the Or-Orco complex and how ions permeate this complex remain unknown. To begin to address the relationship between Or-Orco structure and function, we performed site-directed mutagenesis of all 83 conserved Glu, Asp, or Tyr residues in the silkmoth BmOr-1-Orco pheromone receptor complex and measured functional properties of mutant channels expressed in Xenopus oocytes. 13 of 83 mutations in BmOr-1 and BmOrco altered the reversal potential and rectification index of the BmOr-1-Orco complex. Three of the 13 amino acids (D299 and E356 in BmOr-1 and Y464 in BmOrco) altered both current-voltage relationships and K+ selectivity. We introduced the homologous Orco Y464 residue into Drosophila Orco in vivo, and observed variable effects on spontaneous and evoked action potentials in olfactory neurons that depended on the particular Or-Orco complex examined. Our results provide evidence that a subset of conserved Glu, Asp and Tyr residues in both subunits are essential for channel activity of the heteromeric insect Or-Orco complex. ER -