Recruitment of a ROC1-CUL1 ubiquitin ligase by Skp1 and HOS to catalyze the ubiquitination of I kappa B alpha.
Activation of the transcription factor NF-kappa B in response to proinflammatory stimuli requires the phosphorylation-triggered and ubiquitin-dependent degradation of the NF-kappa B inhibitor, I kappa B alpha. Here, we show the in vitro reconstitution of the phosphorylation-dependent ubiquitination of I kappa B alpha with purified components. ROC1, a novel SCF-associated protein, is recruited by cullin 1 to form a quatemary SCFHOS-ROC1 holenzyme (with Skp1 and the beta-TRCP homolog HOS). SCFHOS-ROC1 binds IKK beta-phosphorylated I kappa B alpha and catalyzes its ubiquitination in the presence of ubiquitin, E1, and Cdc34. ROC1 plays a unique role in the ubiquitination reaction by heterodimerizing with cullin 1 to catalyze ubiquitin polymerization.
Tan
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P
Derald H. Ruttenberg Cancer Center, Mount Sinai School of Medicine, New York, New York 10029, USA.
Fuchs
S Y
SY
Chen
A
A
Wu
K
K
Gomez
C
C
Ronai
Z
Z
Pan
Z Q
ZQ
D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000378:metabolism*; D044842:Cullin Proteins; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051550:I-kappa B Kinase; D020672:I-kappa B Proteins; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D010453:Peptide Synthases / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D044786:S-Phase Kinase-Associated Proteins; D044843:SKP Cullin F-Box Protein Ligases; D014452:Ubiquitins / Q000378:metabolism
D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; C000606204:NFKBIA protein, human; D044786:S-Phase Kinase-Associated Proteins; D014452:Ubiquitins; D000072000:NF-KappaB Inhibitor alpha; D044843:SKP Cullin F-Box Protein Ligases; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; D010453:Peptide Synthases