FIG. 9.

Schematic diagram summarizing the dynamic characteristics of the SPS sensor component interactions. The state I sensor is the complex present in cells grown in the absence of amino acids. The SPS components are present in high levels, represented by the heavy outlines. In analogy to the G-protein-coupled α-factor receptor complex in MATa cells (39), the state I conformation may represent a preactivation complex. States IIa and IIb are transient complexes that rapidly form when cells grown in the absence of amino acids are induced by amino acids. The components in the transient state IIa and IIb sensor undergoing dynamic changes in expression levels are represented by the dashed outlines. The state III conformation is the downregulated complex, and the diminished levels of the components are represented by light outlines. For additional details, see text.