Regulation of cell surface expression of functional pacemaker channels by a motif in the B-helix of the cyclic nucleotide-binding domain

Am J Physiol Cell Physiol. 2008 Sep;295(3):C642-52. doi: 10.1152/ajpcell.00062.2008. Epub 2008 Jul 9.

Abstract

Previous studies have suggested that a portion of the cyclic nucleotide-binding domain (CNBD) of the hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2) "pacemaker" channel, composed of the A- and B-helices and the interceding beta-barrel, confers two functions: inhibition of channel opening in response to hyperpolarization and promotion of cell surface expression. The sequence determinants required for each of these functions are unknown. In addition, the mechanism underlying plasma membrane targeting by this subdomain has been limitedly explored. Here we identify a four-amino acid motif (EEYP) in the B-helix that strongly promotes channel export from the endoplasmic reticulum (ER) and cell surface expression but does not contribute to the inhibition of channel opening. This motif augments a step in the trafficking pathway and/or the efficiency of correct folding and assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs*
  • Amino Acid Sequence
  • Animals
  • Biological Clocks*
  • CHO Cells
  • Cell Membrane / metabolism*
  • Cricetinae
  • Cricetulus
  • Endoplasmic Reticulum / metabolism
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
  • Ion Channel Gating
  • Ion Channels / chemistry
  • Ion Channels / genetics
  • Ion Channels / metabolism*
  • Mice
  • Molecular Sequence Data
  • Potassium Channels
  • Protein Folding
  • Protein Structure, Secondary
  • Protein Transport
  • Transfection

Substances

  • Hcn2 protein, mouse
  • Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels
  • Ion Channels
  • Potassium Channels