Figure 2.

Nucleosome depletion derepresses NFI-dependent transcription of MMTV promoter. (A) Yeast strains with the histone H4 gene under its own promoter or under galactose (Gal) control, and containing a complete MMTV–lacZ reporter with a positioned nucleosome, were transformed with an expression vector for NFI, NFI–VP16, or empty vector (23). β-Galactosidase activities of cultures switched from galactose to glucose (Glu) or kept in galactose are shown. (B) A similar yeast strain with the histone H4 gene under galactose control and carrying a truncated MMTV–lacZ reporter, depicted at the bottom, was assayed as in A. Note the difference in scale between A and B.