FIG. 7.

The strong activation domain VP16 fails to restore activity to inactive proteins. Shown are activities of LexA (A) and VP16 (B) fusion proteins on hb-lacZ and kni-lacZ reporters in yeast cells. The activity of LexA-Bcd and Bcd-VP16 was assigned a value of 100 for each reporter (see the legends to Fig. 6 and 8 for β-galactosidase units). A comparison of panels A and B reveals that VP16 fails to change the relative activities of other proteins, indicating that VP16 cannot restore activity to these proteins. The results further suggest that our proteins are defective in recognizing the natural enhancer elements, as opposed to lacking a functional activation domain.