IKK-i and TBK-1 are enzymatically distinct from the homologous enzyme IKK-2: comparative analysis of recombinant human IKK-i, TBK-1, and IKK-2
| Autor: | Nandini, Kishore, Q Khai, Huynh, Sumathy, Mathialagan, Troii, Hall, Sharon, Rouw, David, Creely, Gary, Lange, James, Caroll, Beverley, Reitz, Ann, Donnelly, Hymavathi, Boddupalli, Rodney G, Combs, Kuniko, Kretzmer, Catherine S, Tripp |
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| Rok vydání: | 2002 |
| Předmět: |
Insecta
Blotting Western Molecular Sequence Data Protein Serine-Threonine Kinases Cell Line Inhibitory Concentration 50 Jurkat Cells Adenosine Triphosphate Serine Animals Humans Protein Isoforms Amino Acid Sequence Cloning Molecular Phosphorylation Binding Sites Dose-Response Relationship Drug NF-kappa B Phosphoric Monoester Hydrolases Recombinant Proteins I-kappa B Kinase Protein Structure Tertiary Enzyme Activation Kinetics Mutagenesis Site-Directed Electrophoresis Polyacrylamide Gel Peptides |
| Zdroj: | The Journal of biological chemistry. 277(16) |
| ISSN: | 0021-9258 |
| Popis: | NF-kappaB is sequestered in the cytoplasm by the inhibitory IkappaB proteins. Stimulation of cells by agonists leads to the rapid phosphorylation of IkappaBs leading to their degradation that results in NF-kappaB activation. IKK-1 and IKK-2 are two direct IkappaB kinases. Two recently identified novel IKKs are IKK-i and TBK-1. We have cloned, expressed, and purified to homogeneity recombinant human (rh)IKK-i and rhTBK-1 and compared their enzymatic properties with those of rhIKK-2. We show that rhIKK-i and rhTBK-1 are enzymatically similar to each other. We demonstrate by phosphopeptide mapping and site-specific mutagenesis that rhIKK-i and rhTBK-1 are phosphorylated on serine 172 in the mitogen-activated protein kinase kinase activation loop and that this phosphorylation is necessary for kinase activity. Also, rhIKK-i and rhTBK-1 have differential peptide substrate specificities compared with rhIKK-2, the mitogen-activated protein kinase kinase activation loop of IKK-2 being a more favorable substrate than the IkappaBalpha peptide. Finally, using analogs of ATP, we demonstrate unique differences in the ATP-binding sites of rhIKK-i, rhTBK-1, and rhIKK-2. Thus, although these IKKs are structurally similar, their enzymatic properties may provide insights into their unique functions. |
| Databáze: | OpenAIRE |
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