Recent studies have demonstrated that p53 binds to specific DNA sequen
ces and the consensus sequence for the p53 binding site has been propo
sed. The p53 binding site has also been shown to act as positive p53-r
esponsive element. Here we report the identification of a GC3 element
that enhances p53-mediated transactivation when placed adjacent to the
consensus p53 site. The GC3 element alone cannot act as a positive p5
3-responsive element. We also show that p53 activates transcription of
the c-erbA-alpha gene through a DNA element that consists of the p53
quarter-sites and GC3 elements. Using gel mobility-shift assay, we ide
ntified a possible GC3 binding factor distinct from p53.