PR001135 (Project)

Description:While much is known about glucose metabolism in yeast, less is known about the receptors and signaling pathways that indicate glucose availability. We obtained metabolic profiles for wildtype and 16 mutants affecting the yeast glucose sensing pathway, comparing 0.05% glucose vs 10 min after glucose addition to 2%. First, we determined that the G protein-coupled receptor (Gpr1/Gpa2) directs early events in glucose utilization while the transceptors (Snf3/Rgt2) regulate subsequent processes and downstream products of glucose metabolism. Whereas the large G protein transmits the signal from its cognate receptor, Ras2 (but not Ras1) integrates responses from both receptor pathways. Second, we determined the relative contributions of the G protein a (Gpa2) and ß (Asc1) subunits to glucose-initiated processes. We determined that Gpa2 is primarily involved in regulating carbohydrate metabolism while Asc1 is primarily involved in amino acid metabolism. Both proteins are involved in regulating purine metabolism. Collectively, our analysis reveals the molecular basis for glucose detection and the earliest events of glucose-dependent signal transduction in yeast.