alphaNAC requires an interaction with c-Jun to exert its transcriptional coactivation

alphaNAC is a transcriptional coactivator known to interact with the N-terminal activation domain of the c-Jun transcription factor. In this article, we describe the identification of the c-Jun interaction domain within the alphaNAC protein. Deletion analysis of alphaNAC indicated that the c-Jun binding site was located in the middle part of the protein, between residues 89 and 129. The deletion of the C-terminal end of alphaNAC, including the c-Jun interacting domain, induced a nuclear translocation of the mutated coactivator. Despite its presence in the nucleus, this deletion mutant did not retain the capacity to coactivate an AP-1 response. These results demonstrate that the interaction between alphaNAC and c-Jun was necessary for the potentiation of theAP-1 transcriptional activity. These data are consistent with a mechanism by which alphaNAC acts as a coactivator for c-Jun-dependent transcription by interacting with the c-Jun N-terminal activation domain.