The heteromeric cyclic nucleotide-gated channel adopts a 3A:1B stoichiometry

Nature. 2002 Nov 14;420(6912):193-8. doi: 10.1038/nature01201.

Abstract

Cyclic nucleotide-gated (CNG) channels are crucial for visual and olfactory transductions. These channels are tetramers and in their native forms are composed of A and B subunits, with a stoichiometry thought to be 2A:2B (refs 6, 7). Here we report the identification of a leucine-zipper-homology domain named CLZ (for carboxy-terminal leucine zipper). This domain is present in the distal C terminus of CNG channel A subunits but is absent from B subunits, and mediates an inter-subunit interaction. With cross-linking, non-denaturing gel electrophoresis and analytical centrifugation, this CLZ domain was found to mediate a trimeric interaction. In addition, a mutant cone CNG channel A subunit with its CLZ domain replaced by a generic trimeric leucine zipper produced channels that behaved much like the wild type, but less so if replaced by a dimeric or tetrameric leucine zipper. This A-subunit-only, trimeric interaction suggests that heteromeric CNG channels actually adopt a 3A:1B stoichiometry. Biochemical analysis of the purified bovine rod CNG channel confirmed this conclusion. This revised stoichiometry provides a new foundation for understanding the structure and function of the CNG channel family.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cattle
  • Cell Line
  • Centrifugation
  • Chromatography, Gel
  • Cross-Linking Reagents
  • Cyclic Nucleotide-Gated Cation Channels
  • Humans
  • Ion Channels / chemistry*
  • Ion Channels / genetics
  • Ion Channels / isolation & purification
  • Ion Channels / metabolism
  • Leucine Zippers / genetics
  • Mice
  • Molecular Sequence Data
  • Mutation
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Protein Subunits
  • Rats
  • Retinal Rod Photoreceptor Cells
  • Structure-Activity Relationship

Substances

  • Cross-Linking Reagents
  • Cyclic Nucleotide-Gated Cation Channels
  • Ion Channels
  • Protein Subunits