The ATF/CREB family consists of transcription factors that function through binding to the cAMP responsive element (CRE) palindromic octanucleotide, TGACCTCA. The best characterized members of this gene family include CREB-1, CREB-2, ATF-1,ATF-2,ATF-3and ATF-4. these transcription factors share highly-related COOH terminal leucine zipper demerization and basic DNA bindings but are highly divergent in their amino terminal domains. Although each of the ATF/CREB proteins bind CREs in their homodimeric form, in cerain instances they also bind as heterodimers, both within the ATF/CREB family and with members of the AP-1 transcription factor family. It has recentlybeen shown that protein kinase A-mediated CREB phosphorylation results in its binding to a 265kDa nuclear protein designated CBP (CREB-binding protein), which may reprecent a CREB co-activator.