Is Kir6.1 a subunit of mitoKATP?

Brian B. Foster, Jasma J. Rucker, Eduardo Marbán

Research output: Contribution to journalArticle

Abstract

The subunit composition of the mitochondrial ATP-sensitive K+-channel (mitoKATP) 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 mitoKATP 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 48 kDa, 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 51 kDa 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 mitoKATP on the basis of immunoreactivity alone.

Original languageEnglish (US)
Pages (from-to)649-656
Number of pages8
JournalBiochemical and Biophysical Research Communications
Volume366
Issue number3
DOIs
StatePublished - Feb 15 2008

Keywords

  • Antibodies
  • Kir6.1
  • Mass spectrometry
  • Mitochondria
  • Potassium channel
  • Preconditioning
  • Protein purification

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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