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Pflügers Archiv

, Volume 442, Issue 6, pp 828–833 | Cite as

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

  • Ian Ashmole
  • Paul A. Goodwin
  • Peter R. Stanfield
Original Article

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.

Cloning Potassium channel Tandem pore 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Ian Ashmole
    • 2
  • Paul A. Goodwin
    • 2
  • Peter R. Stanfield
    • 1
  1. 1.Department of Biological Sciences, The University of Warwick, Coventry CV4 7AL, UK
  2. 2.Ion Channel Group, Department of Cell Physiology and Pharmacology, University of Leicester, PO Box 138, Leicester LE1 9HN, UK

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