The AP-1 repressor, JDP2, is a bona fide substrate for the c-Jun N-terminal kinase.

The Jun dimerization protein 2 (JDP2) is a novel member of the basic leucine zipper family of transcription factors. JDP2 binds DNA as a homodimer and heterodimer with ATF2 and Jun proteins but not with c-Fos proteins. JDP2 overexpression represses activating protein 1 transcription activity. Whereas JDP2 mRNA and protein levels are stable following different cell stimuli, JDP2 is rapidly phosphorylated upon UV irradiation, oxidative stress and low levels of translation inhibitor. The c-Jun N-terminal kinase phosphorylates JDP2 both in vitro and in vivo. JDP2 contains a putative consensus JNK docking-site and a corresponding phosphoacceptor site. Substitution of threonine 148 to an alanine residue blocks JNK-dependent JDP2 phosphorylation. Our data indicate that JDP2 is a bona fide substrate for the c-Jun N-terminal kinase. The precise role of JDP2 phosphorylation on its function is not yet known.