Zinc Finger Homeobox Protein 3 (ZFHX3)

Tissue-specific expression of the human alpha-fetoprotein (AFP) gene is strongly stimulated by an enhancer present 3.3 to 4.9 kb upstream of the transcription initiation site.  To determine the nuclear factor in hepatoma cell lines that interacts with the human AFP enhancer AT motif, Morinaga et al. (1991) screened a hepatoma cDNA expression library with an AFP enhancer fragment that bore the AT motif. They succeeded in isolating a cDNA that can code for an AT motif-binding factor, which they termed ATBF1. This was the largest DNA-binding protein identified to that time and the first protein shown to contain multiple homeodomains and multiple zinc finger motifs. The protein had a predicted mass of 306 kD and contained 4 homeodomains and 17 zinc finger motifs.