Protein kinase A contributes to the negative control of Snf1 protein kinase in XXXX .

@entity268 @entity6773 @entity1 @entity860 @entity16712 @entity16713 @entity375 @entity9787 @entity48509 @entity37038 @entity20883 @entity1919 @entity563 @entity12362 @entity1889 @entity413 @entity12361
Snf1 protein kinase regulates responses to @entity413 limitation and other stresses. Snf1 activation requires phosphorylation of its T-loop @entity1889 by partially redundant upstream kinases ( @entity12361 , @entity12362 , and @entity6773 ). Under favorable conditions, Snf1 is turned off by @entity16712 - @entity9787 protein phosphatase. The @entity16712 mutation causes increased Snf1 activation and slow growth. To identify new components of the Snf1 pathway, we searched for mutations that, like snf1, suppress @entity16712 for the slow-growth phenotype. In addition to mutations in genes encoding known pathway components (SNF1, @entity16713 , and @entity12361 ), we recovered "fast" mutations, designated fst1 and fst2. Unusual morphology of the mutants in the   1278b strains employed here helped us identify fst1 and fst2 as mutations in the RasGAP genes @entity48509 and @entity37038 . Cells lacking @entity48509 , @entity37038 , or @entity20883 , the negative regulatory subunit of @entity1919 ( @entity268 )-dependent protein kinase A (PKA), exhibited reduced Snf1 pathway activation. Conversely, Snf1 activation was elevated in cells lacking the Gpr1 sugar receptor, which contributes to PKA signaling. We show that the Snf1-activating kinase @entity12361 is phosphorylated in vivo on a conserved @entity563 (Ser1074) within an ideal PKA motif. However, this phosphorylation alone appears to play only a modest role in regulation, and @entity12361 is not the only relevant target of the PKA pathway. Collectively, our results suggest that PKA, which integrates multiple regulatory inputs, could contribute to Snf1 regulation under various conditions via a complex mechanism. Our results also support the view that, like its @entity1 counterpart, @entity860 -activated protein kinase (AMPK), @entity375 Snf1 participates in metabolic checkpoint control that coordinates growth with nutrient availability.
