The Ras/protein kinase A pathway acts in parallel with the Mob2/Cbk1 pathway to effect cell cycle progression and proper bud site selection.

In Saccharomyces cerevisiae, Ras proteins connect nutrient availability to cell growth through regulation of protein kinase A (PKA) activity. Ras proteins also have PKA-independent functions in mitosis and actin repolarization. We have found that mutations in MOB2 or CBK1 confer a slow-growth phenotype in a ras2Delta background. The slow-growth phenotype ...
of mob2Delta ras2Delta cells results from a G1 delay that is accompanied by an increase in size, suggesting a G1/S role for Ras not previously described. In addition, mob2Delta strains have imprecise bud site selection, a defect exacerbated by deletion of RAS2. Mob2 and Cbk1 act to properly localize Ace2, a transcription factor that directs daughter cell-specific transcription of several genes. The growth and budding phenotypes of the double-deletion strains are Ace2 independent but are suppressed by overexpression of the PKA catalytic subunit, Tpk1. From these observations, we conclude that the PKA pathway and Mob2/Cbk1 act in parallel to determine bud site selection and promote cell cycle progression.
Mesh Terms:
Actins, Blotting, Northern, Cell Cycle, Cell Cycle Proteins, Cell Division, Cell Survival, Cyclic AMP-Dependent Protein Kinases, Diploidy, Flow Cytometry, Fungal Proteins, G1 Phase, Gene Deletion, Genotype, Haploidy, Intracellular Signaling Peptides and Proteins, Mitosis, Models, Biological, Mutation, Phenotype, Pheromones, Phosphoproteins, Plasmids, Protein-Serine-Threonine Kinases, RNA, S Phase, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Transcription, Genetic, Trehalose
Eukaryotic Cell
Date: Feb. 01, 2004
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