The Caenorhabditis elegans Avermectin Resistance and Anesthetic Response Gene unc-9 Encodes a Member of a Protein Family Implicated in Electrical Coupling of Excitable Cells
Article first published online: 18 NOV 2002
Journal of Neurochemistry
Volume 69, Issue 6, pages 2251–2260, December 1997
How to Cite
Barnes, T. M. and Hekimi, S. (1997), The Caenorhabditis elegans Avermectin Resistance and Anesthetic Response Gene unc-9 Encodes a Member of a Protein Family Implicated in Electrical Coupling of Excitable Cells. Journal of Neurochemistry, 69: 2251–2260. doi: 10.1046/j.1471-4159.1997.69062251.x
- Issue published online: 18 NOV 2002
- Article first published online: 18 NOV 2002
- Received March 14, 1997; revised manuscript received June 10, 1997; accepted July 29, 1997.
- Volatile anesthetic;
- Gap junction;
- OPUS protein;
- Ion channel
Abstract: Mutations in the unc-9 gene of the nematode Caenorhabditis elegans cause abnormal forward locomotion and an egg-retention phenotype. unc-9 mutations also reduce the worms' sensitivity to avermectin and block a form of hypersensitivity to volatile anesthetics. We report here the cloning and molecular characterization of unc-9 and show that it encodes a member of the OPUS family of proteins that is 56% identical to another OPUS protein, UNC-7. It is significant that unc-9 mutants share all phenotypes with unc-7 mutants. Mutants in another gene, unc-124, also share all tested phenotypes with unc-9 mutants, including identical locomotory and egg-laying defects, suggesting that multiple genes are required for the same biochemical function. OPUS proteins are implicated in the function of invertebrate gap junctions, and, based on a new alignment including 24 members from C. elegans, we present a refined model for the structure of OPUS proteins suggesting that oligomers could form a hydrophilic pore. We also show that alteration of highly conserved proline residues in UNC-9 leads to a cold sensitivity that likely affects a step in protein expression rather than function. Finally, we speculate on the basis of the avermectin resistance and anesthetic response phenotypes.