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J Biol Chem. 2001 Jun 15;276(24):20999-1003. Epub 2001 Mar 9.

Glutathione S-transferase P1-1 (GSTP1-1) inhibits c-Jun N-terminal kinase (JNK1) signaling through interaction with the C terminus.

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  • 1Department of Pharmacology, Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111, USA.

Abstract

c-Jun N-terminal kinase (JNK)-mediated cell signaling pathways are regulated endogenously in part by protein-protein interactions with glutathione S-transferase P1-1 (GSTP1-1) (). Using purified recombinant proteins, combined with fluorescence resonance energy transfer technology, we have found that the C terminus of JNK is critical to the interaction with GSTP1-1. The apparent K(d) for full-length JNK was 188 nm and for a C-terminal fragment (residues 200-424) 217 nm. An N-terminal fragment (residues 1-206) did not bind to GSTP1-1. Increased expression of the C-terminal JNK fragment in a tetracycline-inducible transfected NIH3T3 cell line produced a concentration-dependent increase in the kinase activity of JNK under normal, unstressed growth conditions indicating a dominant-negative effect. This suggests that the fragment can compete with endogenous full-length functional JNK resulting in dissociation of the GSTP1-1-JNK interaction and concomitant JNK enzyme activation. By using an antibody to hemagglutinin-tagged C-JNK, a concentration-dependent co-immunoprecipitation of GSTP1-1 was achieved. These data provide evidence for direct interactions between the C-terminal of JNK and GSTP1-1 and a rationale for considering GSTP1-1 as a critical ligand-binding protein with a role in regulating kinase pathways.

PMID:
11279197
[PubMed - indexed for MEDLINE]
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