Subunit composition of a DEG/ENaC mechanosensory channel of Caenorhabditis elegans.
Caenorhabditis elegans senses gentle touch in the six touch receptor neurons (TRNs) using a mechanotransduction complex that contains the pore-forming degenerin/epithelial sodium channel (DEG/ENaC) proteins MEC-4 and MEC-10. Past work has suggested these proteins interact with the paraoxonase-like MEC-6 and the cholesterol-binding stomatin-like MEC-2 proteins. Using single molecule optical imaging in Xenopus oocytes, we found that MEC-4 forms homotrimers and MEC-4 and MEC-10 form 4:4:10 heterotrimers. MEC-6 and MEC-2 do not associate tightly with these trimers and do not influence trimer stoichiometry, indicating that they are not part of the core channel transduction complex. Consistent with the in vitro data, MEC-10, but not MEC-6, formed puncta in TRN neurites that colocalize with MEC-4 when MEC-4 is overexpressed in the TRNs.
Department of Biological Sciences, Columbia University, New York, NY 10027;
Yushu
Y
Chen
Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720.
Shashank
S
Bharill
Department of Molecular and Cell Biology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA 94720.
Ehud Y
EY
Isacoff
Department of Biological Sciences, Columbia University, New York, NY 10027; mc21@columbia.edu.
Martin
M
Chalfie
D000818:Animals; D030801:Animals, Genetically Modified; D043303:Aryldialkylphosphatase / Q000737:chemistry; D017173:Caenorhabditis elegans / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000502:physiology*; D004594:Electrophysiology; D053503:Epithelial Sodium Channels / Q000737:chemistry; D008465:Mechanoreceptors / Q000502:physiology*; D040542:Mechanotransduction, Cellular / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009865:Oocytes / Q000166:cytology; D011485:Protein Binding; D055503:Protein Multimerization; D014982:Xenopus laevis
D029742:Caenorhabditis elegans Proteins; C094927:Deg-1 protein, C elegans; D053503:Epithelial Sodium Channels; C115871:Mec-4 protein, C elegans; D008565:Membrane Proteins; C085942:MEC-10 protein, C elegans; C470181:MEC-6 protein, C elegans; D043303:Aryldialkylphosphatase
DEG/ENaC proteins; channel stoichiometry; mechanosensory channels