SP1 AFFINITY FOR GC-RICH ELEMENTS CORRELATES WITH ORNITHINE DECARBOXYLASE PROMOTER ACTIVITY

The highly conserved ornithine decarboxylase (E.C.4.1.1.17) promoter contains multiple binding sites for Spl within the first 400 bp of the cap site. Therefore the ability of-individual Spl elements to confer transactivation alone or in combination was tested. We show that different Spl sites vary in their affinity for Spl and that increasing affinity correlates with enhancer activity. In addition, several adjacent Spl sites synergistically enhanced promoter activity. of promoter transactivation correlated with both the number of GC-rich elements and their affinity for Spl protein. (C) 1995 Academic Press, Inc.