Evidence against functional heteromultimerization of the K(ATP) channel subunits Kir6.1 and Kir6.2

Jegatheesan Seharaseyon, Norihito Sasaki, Andreas Ohler, Toshiaki Sato, Heather Fraser, David C. Johns, Brian O'Rourke, Eduardo Marbán

Research output: Contribution to journalArticlepeer-review

Abstract

K(ATP) channels consist of pore-forming potassium inward rectifier (Kir6.x) subunits and sulfonylurea receptors (SURs). Although Kir6.1 or Kir6.2 coassemble with different SUR isoforms to form heteromultimeric functional K(ATP) channels, it is not known whether Kir6.1 and Kir6.2 coassemble with each other. To define the molecular identity of K(ATP) channels, we used adenoviral gene transfer to express wild-type and dominant- negative constructs of Kir6.1 and Kir6.2 in a heterologous expression system (A549 cells) and in native cells (rabbit ventricular myocytes). Dominant- negative (DN) Kir6.2 gene transfer suppressed current through heterologously expressed SUR2A + Kir6.2 channels. Conversely, DN Kir6.1 suppressed SUR2B + Kir6.1 current but had no effect on coexpressed SUR2A + Kir6.2. We next probed the ability of Kir6.1 and Kir6.2 to affect endogenous K(ATP) channels in adult rabbit ventricular myocytes, using adenoviral vectors to achieve efficient gene transfer. Infection with the DN Kir6.2 virus for 72 h suppressed pinacidil-inducible K(ATP) current density measured by whole-cell patch clamp. However, there was no effect of infection with the DN Kir6.1 on the K(ATP) current. Based on these functional assays, we conclude that Kir6.1 and Kir6.2 do not heteromultimerize with each other and that Kir6.2 is the sole K(ATP) pore-forming subunit in the surface membrane of heart cells.

Original languageEnglish (US)
Pages (from-to)17561-17565
Number of pages5
JournalJournal of Biological Chemistry
Volume275
Issue number23
DOIs
StatePublished - Jun 9 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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