Direct involvement of the ubiquitin-conjugating enzyme Ubc9/Hus5 in the degradation of IkappaBalpha.
basic_science · Level V
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- Record sourced from PubMed, PMID 9223278.
- Also identified by PMC identifier 21520.
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Abstract
The NF-kappaB/Rel proteins are sequestered in the cytoplasm in association with IkappaBalpha. In response to external signals, IkappaBalpha is phosphorylated, multi-ubiquitinated, and degraded by proteasomes, thereby releasing NF-kappaB/Rel proteins to migrate to the nucleus. We have cloned a mouse ubiquitin-conjugating enzyme (mE2), which associates with IkappaBalpha. mE2 is homologous to the yeast Ubc9/Hus5 ubiquitin-conjugating enzyme. A transdominant-negative mutant of mE2 had no effect on phosphorylation of IkappaBalpha, but delayed its degradation. Correspondingly, tumor necrosis factor-alpha-inducible NF-kappaB activity was diminished. We propose that mE2 is directly involved in the ubiquitin conjugation of IkappaBalpha, a pivotal step in its degradation pathway.
Medical subject headings
- DNA-Binding Proteins
- Fungal Proteins
- I-kappa B Proteins
- Ligases
- Schizosaccharomyces pombe Proteins
- Ubiquitin-Conjugating Enzymes