Cys palmitoylation of the beta subunit modulates gating of the epithelial sodium channel

J Biol Chem. 2010 Oct 1;285(40):30453-62. doi: 10.1074/jbc.M110.151845. Epub 2010 Jul 27.


The epithelial Na(+) channel (ENaC) is comprised of three homologous subunits (α, β, and γ) that have a similar topology with two transmembrane domains, a large extracellular region, and cytoplasmic N and C termini. Although ENaC activity is regulated by a number of factors, palmitoylation of its cytoplasmic Cys residues has not been previously described. Fatty acid-exchange chemistry was used to determine whether channel subunits were Cys-palmitoylated. We observed that only the β and γ subunits were modified by Cys palmitoylation. Analyses of ENaCs with mutant β subunits revealed that Cys-43 and Cys-557 were palmitoylated. Xenopus oocytes expressing ENaC with a β C43A,C557A mutant had significantly reduced amiloride-sensitive whole cell currents, enhanced Na(+) self-inhibition, and reduced single channel P(o) when compared with wild-type ENaC, while membrane trafficking and levels of surface expression were unchanged. Computer modeling of cytoplasmic domains indicated that β Cys-43 is in proximity to the first transmembrane α helix, whereas β Cys-557 is within an amphipathic α-helix contiguous with the second transmembrane domain. We propose that β subunit palmitoylation modulates channel gating by facilitating interactions between cytoplasmic domains and the plasma membrane.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amiloride / pharmacology
  • Amino Acid Substitution
  • Animals
  • Cell Line
  • Cell Membrane / metabolism*
  • Computer Simulation
  • Dogs
  • Epithelial Sodium Channels / genetics
  • Epithelial Sodium Channels / metabolism*
  • Ion Channel Gating / physiology*
  • Lipoylation / physiology*
  • Mice
  • Models, Molecular
  • Mutation
  • Mutation, Missense
  • Oocytes
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Protein Transport / physiology
  • Sodium / metabolism*
  • Sodium Channel Blockers / pharmacology
  • Xenopus laevis


  • Epithelial Sodium Channels
  • Sodium Channel Blockers
  • Amiloride
  • Sodium