Steady-state transcript levels of cytochrome c oxidase genes during human myogenesis indicate subunit switching of subunit VIa and co-expression of subunit VIIa isoforms

Biochim Biophys Acta. 1992 Jun 9;1139(1-2):155-62. doi: 10.1016/0925-4439(92)90095-5.


Steady-state levels of the mitochondrial rRNAs, of mRNAs for mitochondrially and nuclear-encoded subunits of cytochrome c oxidase and for the beta subunit of ATP synthase were assessed by Northern blot hybridizations during the in vitro differentiation of human myoblasts. Transcript levels of the so-called liver-type form of subunit VIa of cytochrome c oxidase diminished during the course of differentiation, while transcription of the so-called heart-type form was induced. Transcripts for the liver-type form and for the heart-type form of subunit VIIa of cytochrome c oxidase were detected in all myogenic cultures; the levels of the heart-type form progressively increased during the course of differentiation. The levels of the other transcripts studied did not change substantially. The results suggest subunit switching of subunit VIa and co-expression of subunit VIIa isoforms during myogenesis. The differential changes in mRNA levels of the heart-type subunits VIa and VIIa and the differential changes in mRNA levels of the liver-type subunits VIa and VIIa demonstrate that different transcriptional regulation mechanisms are present for both heart-type genes as well as for both liver-type genes.

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Adult
  • Cells, Cultured
  • Electron Transport Complex IV / chemistry
  • Electron Transport Complex IV / genetics*
  • Electron Transport Complex IV / metabolism
  • Female
  • Humans
  • Isoenzymes / chemistry
  • Isoenzymes / genetics*
  • Isoenzymes / metabolism
  • Male
  • Mitochondria, Muscle / enzymology
  • Mitochondria, Muscle / metabolism
  • Muscles / cytology
  • Muscles / enzymology*
  • RNA, Messenger / metabolism
  • RNA, Ribosomal, 16S / genetics
  • Transcription, Genetic*


  • Isoenzymes
  • RNA, Messenger
  • RNA, Ribosomal, 16S
  • Electron Transport Complex IV
  • Adenosine Triphosphatases