title: Possible involvement of RAS-encoded proteins in glucose-induced inositolphospholipid turnover in Saccharomyces cerevisiae.
abstract: Incubation of yeast Saccharomyces cerevisiae at very low (0.02%) glucose levels led to arrest of the cell cycle at the G0/G1 phase. Readdition of glucose to these "starved" yeast resulted in cell proliferation. In glucose-starved yeast, glucose stimulated 32P incorporation into phosphatidic acid, phosphatidylinositol, phosphatidylinositol monophosphate, and phosphatidylinositol bisphosphate but not into phosphatidylethanolamine and phosphatidylcholine. Preincubation of yeast with [3H]inositol and subsequent exposure to glucose resulted in rapid formation of [3H]inositol monophosphate and [3H]inositol trisphosphate, presumably derived from phosphatidylinositol and phosphatidylinositol bisphosphate. Under similar conditions, glucose elicited both efflux and influx of Ca2+ in yeast. Glucose-induced 32P incorporation into inositolphospholipids and formation of [3H]inositol phosphates were more pronounced in RAS-related mutants such as ras1, ras1 ras2 bcy1, and RAS2Val19 than in the wild-type strain. These results strongly suggest that glucose stimulates inositolphospholipid turnover, Ca2+ mobilization, and subsequent cell proliferation in a manner similar to that of growth factors with mammalian cells, and that RAS-encoded proteins are involved in regulation of this glucose-induced inositolphospholipid turnover in yeast.
mesh_terms: D002118:Calcium / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D000242:Cyclic AMP / Q000096:biosynthesis; D019204:GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005947:Glucose / Q000494:pharmacology*; D007295:Inositol Phosphates / Q000378:metabolism*; D009154:Mutation; D011493:Protein Kinase C / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013403:Sugar Phosphates / Q000378:metabolism*; D010738:Type C Phospholipases / Q000032:analysis
chemical_list: D007295:Inositol Phosphates; D013403:Sugar Phosphates; D000242:Cyclic AMP; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins; D005947:Glucose; D002118:Calcium