Figure 1.—

A schematic structure of IME1 5′ untranslated region. The MAT signal mediates repression activity of two elements UCS3 and UCS4. The carbon source signal is transmitted to UCS1, UASru, and IREu, which function as repression elements in the presence of glucose. In addition, UASru IREu and UASrm function as activation elements in the absence of glucose and the presence of acetate as the sole carbon source. Preliminary data suggest that the activity of UASv requires the absence of glucose as well as nitrogen. UCS1 also functions as a negative element in the presence of nitrogen. Solid boxes, elements required for transcriptional activation; open boxes, elements required for transcriptional repression. A positive role is marked with an arrow, a negative role by a line. Larger effects are denoted by thick lines while lesser effects are denoted by thin lines. Putative regulation is marked with a dashed line. Known regulators of IME1 transcription are shown.