Post-transcriptional regulation of tissue-specific isoforms. A bovine cytosolic RNA-binding protein, COLBP, associates with messenger RNA encoding the liver-form isopeptides of cytochrome c oxidase

J Biol Chem. 1993 May 15;268(14):10659-67.


Regulation of the liver isopeptides of bovine cytochrome c oxidase is reported to be post-transcriptional. Extensive interspecies sequence homologies exist in the 3'-untranslated regions for transcripts encoding these liver isoforms, suggesting that these regions may be involved in mediating regulation of mRNA expression. To explore this possibility, several bovine tissue homogenates were assayed for any trans-acting factors that recognized the transcript encoding the liver isoform of subunit VIII (BCOL8). Such a protein factor (COLBP: cytochrome c oxidase L-form transcript-binding protein) was identified in liver, kidney, and lung tissue and was shown to require free sulfhydryl groups for activity. No binding activity, however, was found in muscle-type homogenates. Furthermore, this binding protein also recognized the subunit VIIa-liver transcript but was unable to associate with the mRNA encoding the heart isoform of subunit VIII. Intriguingly, the tissue-specific distribution of COLBP activity parallels the presence of the liver isopeptides in the mature oxidase complex. It is therefore suggested that COLBP may mediate the tissue-specific regulation of cytochrome c oxidase liver isoform mRNA expression.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites
  • Cattle
  • Cloning, Molecular
  • Cytosol / metabolism
  • DNA / genetics
  • Electron Transport Complex IV / biosynthesis
  • Electron Transport Complex IV / genetics*
  • Escherichia coli / genetics
  • Glutamate Dehydrogenase / metabolism*
  • Humans
  • Isoenzymes / biosynthesis
  • Isoenzymes / genetics*
  • Kinetics
  • Liver / enzymology*
  • Molecular Sequence Data
  • Plasmids
  • RNA Processing, Post-Transcriptional*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • RNA-Binding Proteins / metabolism*
  • Rats
  • Sequence Homology, Nucleic Acid
  • Transcription, Genetic


  • Isoenzymes
  • RNA, Messenger
  • RNA-Binding Proteins
  • DNA
  • Glutamate Dehydrogenase
  • Electron Transport Complex IV