Sequential autophosphorylation steps in the interleukin-1 receptor-associated kinase-1 regulate its availability as an adapter in interleukin-1 signaling.
J Biol Chem
; 279(7): 5227-36, 2004 Feb 13.
Article
em En
| MEDLINE
| ID: mdl-14625308
ABSTRACT
The interleukin-1 receptor-associated kinase 1 (IRAK-1) is an important adapter in the signaling complex of the Toll/interleukin-1 (IL-1) receptor family. Formation of the signaling IL-1 receptor complex results in the activation and hyperphosphorylation of IRAK-1, which leads to a pronounced shift of its apparent molecular mass in gel electrophoresis. Presently, the individual residues phosphorylated in IRAK-1 and the consequences for IRAK-1 function are unknown. We define sequential phosphorylation steps in IRAK-1, which are, in vitro, autophosphorylation. First, IRAK-1 is phosphorylated at Thr209. By fluorescence energy transfer experiments, we demonstrate that Thr209 phosphorylation results in a conformational change of the kinase domain, permitting further phosphorylations to take place. Substitution of Thr209 by alanine results in a kinase-inactive IRAK-1. Second, Thr387 in the activation loop is phosphorylated, leading to full enzymatic activity. Third, IRAK-1 autophosphorylates several times in the proline-, serine-, and threonine-rich ProST region between the N-terminal death domain and kinase domain. Hyperphosphorylation of this region leads to dissociation of IRAK-1 from the upstream adapters MyD88 and Tollip but leaves its interaction with the downstream adapter TRAF6 unaffected. This identifies IRAK-1 as a novel type of adapter protein, which employs its own kinase activity to introduce negative charges adjacent to the protein interaction domain, which anchors IRAK-1 at the active receptor complex. Thus, IRAK-1 regulates its own availability as an adapter molecule by sequential autophosphorylation.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas Quinases
/
Interleucina-1
/
Peptídeos e Proteínas de Sinalização Intracelular
Tipo de estudo:
Prognostic_studies
/
Risk_factors_studies
Limite:
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
2004
Tipo de documento:
Article
País de afiliação:
Alemanha