A HUMAN ALPHA-FETOPROTEIN ENHANCER-BINDING PROTEIN, ATBF1, CONTAINS 4 HOMEODOMAINS AND 17 ZINC FINGERS

We have isolated a full-length cDNA encoding a protein (ATBF1) that binds to an AT-rich motif in the human alpha-fetoprotein gene enhancer. The amino acid sequence deduced from the cDNA revealed that this is the largest DNA-binding protein (306 kDa) known to date, containing four homeodomains, 17 zinc finger motifs, and a number of segments potentially involved in transcriptional regulation. Although the exact function of this protein has not been determined, these structural features suggest that ATBF1 plays a transcriptional regulatory role.