TASK-5, a novel member of the tandem pore K+ channel family

Pflugers Arch. 2001 Sep;442(6):828-33. doi: 10.1007/s004240100620.

Abstract

We have cloned a novel member of the tandem pore K+ channel family from human brain cDNA. The novel cDNA encodes a 330-residue polypeptide of predicted molecular mass 36 kDa. We have named the channel TASK-5 owing to its sequence homology with TASK-1 and TASK-3. TASK-5 mRNA is expressed in pancreas, liver, kidney, lung, ovary, testis and heart. However, expression of TASK-5 in heterologous systems failed to elicit ionic currents. Removal of a putative endoplasmic reticulum retention sequence did not alter this finding and the distribution of channel proteins in HEK293 cells was similar for both TASK-1 and TASK-5. We tested whether TASK-5 could form heteromers with TASK-1. We show a mutant form of TASK-1 (H98N) to have a radically reduced sensitivity to acidification. Proton sensitivity could be rescued by injecting equimolar amounts of wild-type and mutant TASK-1 cRNA into Xenopus oocytes; the effect was that expected if half the channels formed are heteromers. Co-expression of TASK-5 with TASK-1 H98N does not affect the proton sensitivity of mutant TASK-1; thus TASK-5 appears not to form heteromers with TASK-1. Nonetheless, TASK-5 may require some other, unidentified partner subunit to form functional channels in the plasma membrane or it may form a channel in an intracellular organelle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Brain Chemistry*
  • Cloning, Molecular*
  • DNA, Complementary / chemistry
  • DNA, Complementary / genetics
  • Dimerization
  • Gene Expression
  • Green Fluorescent Proteins
  • Humans
  • Hydrogen-Ion Concentration
  • Luminescent Proteins / genetics
  • Microscopy, Confocal
  • Molecular Sequence Data
  • Nerve Tissue Proteins*
  • Organ Specificity
  • Potassium Channels / chemistry
  • Potassium Channels / genetics*
  • Potassium Channels, Tandem Pore Domain*
  • RNA, Messenger / analysis
  • Recombinant Fusion Proteins
  • Sequence Analysis, DNA
  • Sequence Homology
  • Tissue Distribution
  • Transfection

Substances

  • DNA, Complementary
  • KCNK15 protein, human
  • Luminescent Proteins
  • Nerve Tissue Proteins
  • Potassium Channels
  • Potassium Channels, Tandem Pore Domain
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • potassium channel subfamily K member 3