Characterization of a minimal SAC1 promoter region sufficient for regulated expression. (A) Diagram depicting deletion constructs. The constructs were fused to the open reading frame of GFP in a CEN-based vector. The plasmids were introduced into a wild-type strain background and promoter activity determined by measurement of relative GFP expression levels in cell extracts. (B) Expression of the GFP reporter. Wild-type and sac1 Δ yeast cells transformed with a CEN-based plasmid containing the SAC1(-100/-1)-GFP fusion construct were grown to early log phase at 30°C. Cell extracts were analyzed by SDS-PAGE and immunoblotting using anti-GFP and anti-glucose-6-phosphate dehydrogenase (Zwf1p) antibodies. (C) Quantitation of relative GFP expression levels. Data are from at least three independent experiments (+/-SE).