Figure 1.

Fusion of Bas1p and Bas2p leads to constitutive expression of their target genes. (A) In vivo effect of a Bas1p–Bas2p fusion on ADE1–LacZ reporter gene activatiom. Y329 (gcn4bas1BAS2) and L4233 (gcn4bas1bas2) cells were co-transformed with a plasmid carrying the ADE1–LacZ fusion and either the B836 plasmid (empty vector, lane –) or the P79 plasmid encoding wild-type Bas1p (BAS1) or the B273 plasmid encoding the Bas1p–Bas2p fusion (BAS1–BAS2). β-Galactosidase (β-Gal) assays were performed on exponentially growing cells in the presence (red boxes) or absence (yellow boxes) of adenine as described in Materials and Methods. (B) In vivo effect of the Bas1p–Bas2p fusion on endogenous HIS gene expression. Y329, Y330 (gcn4BAS1bas2) and L4233 cells were transformed with either the B836 plasmid (vector), the p79 plasmid or the B273 plasmid. Serial dilutions of the cells (10⁴, 10³, 10² and 10 cells) were spotted on SC medium lacking uracil and supplemented (left) or not (right) with histidine. Cells were grown for 36 h at 30°C.