Is Kir6.1 a Subunit of mitoK(ATP)?

Biochem Biophys Res Commun. 2008 Feb 15;366(3):649-56. doi: 10.1016/j.bbrc.2007.11.154. Epub 2007 Dec 7.

Abstract

The subunit composition of the mitochondrial ATP-sensitive K(+)-channel (mitoK(ATP)) is unknown, though some suspect a role for the inward rectifier, Kir6.1, based largely on antibody studies of heart mitochondria. To ascertain the molecular identity of mitoK(ATP) we therefore sought to purify this putative mitochondrial Kir6.1, and conclusively identify the subunits by mass spectrometry. Immunoblots, conducted with two commercially available antibodies, revealed two distinct signals in isolated heart mitochondria, of 51 and 48kDa, respectively. Localization was confirmed by either immuno-gold electron microscopy or by immunofluorescence. Each putative Kir6.1 species was extracted, purified, and identified by LC-MS/MS. The 51kDa band was identified as NADH-dehydrogenase flavoprotein 1, while the preponderant protein in the 48-kDa band was mitochondrial isocitrate dehydrogenase (NADP form). 1D-, 2D-, and native gel analyses were consistent with these assignments. The data suggest it is premature to assign Kir6.1 a role in mitoK(ATP) on the basis of immunoreactivity alone.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cells, Cultured
  • KATP Channels
  • Mitochondria, Heart / chemistry*
  • Mitochondria, Heart / metabolism*
  • Molecular Sequence Data
  • Potassium Channels / chemistry*
  • Potassium Channels / metabolism*
  • Potassium Channels, Inwardly Rectifying / chemistry*
  • Potassium Channels, Inwardly Rectifying / metabolism*
  • Protein Subunits

Substances

  • KATP Channels
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Protein Subunits
  • mitochondrial K(ATP) channel
  • uK-ATP-1 potassium channel