Cloning and characterization of a novel member of the human ATF/CREB family: ATF2 deletion, a potential regulator of the human DNA polymerase beta promoter.

The solitary cAMP response element (CRE)1 in the human DNA polymerase beta (beta-pol) core promoter plays a key role in both basal expression and the DNA-alkylating agent response of the promoter. To further understand the role of the CRE in the regulation of this promoter, we searched for novel CRE-binding proteins by using a 32P-labeled beta-pol CRE oligodeoxynucleotide and a human cDNA expression library constructed in phage lambda. A total of fourteen phage clones were isolated, corresponding to various members of the CRE-binding protein family. One of these clones, termed ATF2 deletion (ATF2d), encodes a novel ATF2 isoform and was chosen for further characterization in this study. Relative to ATF2 mRNA, this clone contains an internal 97-nt deletion and a unique 3' region. The 97-nt deletion causes a frame shift, resulting in a ATF2-like polypeptide of approximately 60 kDa. ATF2d retains the bZIP domain of ATF2, lacks the N-terminal zinc-finger region, and includes novel characteristics in its N- and C-terminal regions.