Identification of the Human β-Actin Enhancer and Its Binding Factor

An enhancer of the human beta-actin gene and a factor that specifically interacts with it were detected. A mobility shift assay showed that the factor bound to the 25-base-pair sequence (between +759 and +783 downstream from the cap site) with high specificity. This finding correlated with those of DNase I protection and exonuclease III digestion assays. This binding region of the beta-actin enhancer contained a hyphenated dyad symmetry and an enhancer core-like sequence. In vitro competition experiments indicated that the factor did not bind to the simian virus 40 enhancer core region.