| Autor: |
Strack, P, Caligiuri, M, Pelletier, M, Boisclair, M, Theodoras, A, Beer-Romero, P, Glass, S, Parsons, T, Copeland, R A, Auger, K R, Benfield, P, Brizuela, L, Rolfe, M |
| Předmět: |
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| Zdroj: |
Oncogene; 7/20/2000, Vol. 19 Issue 31, p3529, 8p |
| Abstrakt: |
NFκB is an important transcriptional regulator of multiple pro-inflammatory genes. In non-stimulated cells NFκB is anchored in the cytoplasm via the inhibitory protein IκBα. Following exposure to diverse pro-inflammatory signals (e.g. TNFα, IL1, LPS) various signal transduction cascades are initiated converging on the IκB kinase (IKK). IKK phosphorylates IκBα on serines 32 and 36 signaling the inhibitory protein for ubiquitin-mediated degradation. The SCFβ-TRCP complex is the ubiquitin ligase responsible for mediating phosphorylation dependent ubiquitination of IκBα. Here we reconstitute phosphorylation dependent ubiquitination of IκBα using recombinant components. Our results suggest that the cullin specificity of the SCF complex may reflect its ability to associate with Rbx1. We demonstrate specific ubiquitination of IκBα by Ubc3 and Ubc4 in a phosphorylation and SCFβ-TRCP dependent manner and that both are capable of associating with the SCFβ-TRCP complex isolated from human cells. Finally, we show that Ubc4 is in excess to Ubc3 in THP.1 cells and 19 times more efficient in catalyzing the reaction, suggesting that Ubc4 is the preferentially used Ubc in this reaction in vivo. Our results also suggest that ubiquitin is transferred directly from the Ubc to phospho-IκBα in a SCFβ-TRCP dependent reaction. Oncogene (2000) 19, 3529–3536 [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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