title: Dual regulation of the yeast CDC28-p40 protein kinase complex: cell cycle, pheromone, and nutrient limitation effects.
abstract: A 40 kd polypeptide that coprecipitates with the CDC28 gene product in immune complexes is specifically phosphorylated by the CDC28 protein kinase. Using this reaction, we detect activity only in extracts from dividing G1 phase cells. Exit from G1 by entry into S phase or the preconjugatory state induced by mating pheromone correlates with loss of p40 phosphorylation activity. Inactive extracts from cdc28 mutants complement extracts from cells arrested in S or M phase, suggesting that non-G1 cells are deficient in an exchangeable activating factor. Stationary and pheromone-treated cultures are rich in this exchangeable factor, but possess an inactive kinase that is not activated by complementation. cAMP-deficient mutants resemble stationary cells.
mesh_terms: D000262:Adenylyl Cyclases / Q000502:physiology; D001562:Benzimidazoles / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D000242:Cyclic AMP / Q000502:physiology; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000502:physiology*; D006918:Hydroxyurea / Q000494:pharmacology; D000072235:Mating Factor; D008954:Models, Biological; D015739:Nocodazole; D010455:Peptides / Q000502:physiology; D010750:Phosphoproteins; D010766:Phosphorylation; D011494:Protein Kinases / Q000276:immunology / Q000502:physiology*; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development*; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000201:enzymology
chemical_list: D001562:Benzimidazoles; D050756:Cyclin-Dependent Kinase Inhibitor Proteins; D005656:Fungal Proteins; D010455:Peptides; D010750:Phosphoproteins; C086926:SIC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D000242:Cyclic AMP; D011494:Protein Kinases; D000262:Adenylyl Cyclases; D015739:Nocodazole; D006918:Hydroxyurea