Cloning and functional expression of a novel degenerin-like Na+ channel gene in mammals

J Physiol. 1999 Sep 1;519 Pt 2(Pt 2):323-33. doi: 10.1111/j.1469-7793.1999.0323m.x.


1. A degenerate polymerase chain reaction (PCR) homology screening procedure was applied to rat brain cDNA in order to identify novel genes belonging to the amiloride-sensitive Na+ channel and degenerin (NaC/DEG) family of ion channels. A single gene was identified that encodes a protein related to but clearly different from the already cloned members of the family (18-30 % amino acid sequence identity). Phylogenetic analysis linked this protein to the group of ligand-gated channels that includes the mammalian acid-sensing ion channels and the Phe-Met-Arg-Phe-amide (FMRFamide)-activated Na+ channel. 2. Expression of gain-of-function mutants after cRNA injection into Xenopus laevis oocytes or transient transfection of COS cells induced large constitutive currents. The activated channel was amiloride sensitive (IC50, 1.31 microM) and displayed a low conductance (9-10 pS) and a high selectivity for Na+ over K+ (ratio of the respective permeabilities, PNa+/PK+ >= 10), all of which are characteristic of NaC/DEG channel behaviour. 3. Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analysis revealed a predominant expression of its mRNA in the small intestine, the liver (including hepatocytes) and the brain. This channel has been called the brain-liver-intestine amiloride-sensitive Na+ channel (BLINaC). 4. Corresponding gain-of-function mutations in Caenorhabditis elegans degenerins are responsible for inherited neurodegeneration in the nematode. Besides the BLINaC physiological function that remains to be established, mutations in this novel mammalian degenerin-like channel might be of pathophysiological importance in inherited neurodegeneration and liver or intestinal pathologies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acid Sensing Ion Channels
  • Amino Acid Sequence
  • Animals
  • Biophysical Phenomena
  • Biophysics
  • Blotting, Northern
  • COS Cells
  • Chromosome Mapping
  • Cloning, Molecular
  • Degenerin Sodium Channels
  • Epithelial Sodium Channels
  • In Situ Hybridization, Fluorescence
  • Ion Channels / biosynthesis*
  • Ion Channels / genetics
  • Liver / cytology
  • Liver / drug effects
  • Liver / metabolism
  • Mice
  • Mice, Inbred BALB C
  • Molecular Sequence Data
  • Nerve Tissue Proteins / biosynthesis*
  • Nerve Tissue Proteins / genetics
  • Oocytes / metabolism
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / isolation & purification
  • Rats
  • Rats, Wistar
  • Reverse Transcriptase Polymerase Chain Reaction
  • Sodium Channels / biosynthesis*
  • Sodium Channels / genetics*
  • Tissue Distribution
  • Xenopus


  • Acid Sensing Ion Channels
  • Asic2 protein, rat
  • Degenerin Sodium Channels
  • Epithelial Sodium Channels
  • Ion Channels
  • Nerve Tissue Proteins
  • RNA, Messenger
  • Sodium Channels