Degradation of Id proteins by the ubiquitin-proteasome pathway

Mangkey A. Bounpheng, Joseph J. Dimas, Sherry G. Dodds, Barbara A. Christy

Research output: Contribution to journalArticlepeer-review

101 Scopus citations


Id proteins act as negative regulators of bHLH transcription factors by forming transcriptionally inactive protein complexes. The proposed function of these proteins includes promotion of cell growth and cell cycle progression, induction of apoptosis, and inhibition of cellular differentiation. We investigated the role of the ubiquitin-mediated proteolytic pathway in the degradation of the Id3 protein. We found Id3 to be a short-lived protein and estimated the half-life to be ~20 min in 293 cells. Using specific inhibitors of the 26S proteasome and mutant fibroblast cells with a temperature-sensitive defect in the essential E1 ubiquitin- activating enzyme, we show that Id3 and the related Id1 and Id2 proteins are degraded through the ubiquitin-proteasome pathway. We found the Id4 protein to be much less sensitive to inhibitors of the 26S proteasome, but its degradation was dependent on the E1 enzyme. In addition, we observed that coexpression of the bHLH protein E47 with Id3 significantly reduced the rate of degradation of Id3, suggesting that Id3 is less susceptible to degradation by the 26S proteasome when complexed to a bHLH protein. - Bounpheng, M. A., Dimas, J. J., Dodds, S. G., Christy, B. A. Degradation of Id proteins by the ubiquitin-proteasome pathway.

Original languageEnglish (US)
Pages (from-to)2257-2264
Number of pages8
JournalFASEB Journal
Issue number15
StatePublished - Jan 1 1999


  • 26S proteasome
  • Dominant-negative regulators
  • Helix-loop-helix

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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