TORC1 and PKA signalling pathways

De VirgilioLab


Keywords: Nutrient signal transduction; quiescence (entry into and exit from G0); protein kinase (PKA);
TOR complex 1 (TORC1); PAS kinase Rim15; EGO complex; yeast

TORC1 and PKA signalling pathways

TORC1 and PKA signalling pathways
Diagram of the TORC1 and PKA signalling network in budding yeast. TORC1, pictured as a dimer, is found at the upper-left corner. The domains found in TOR are indicated, as are the other TORC1 subunits. TORC1 promotes cell growth by stimulating anabolic processes such as translation initiation and permease activity (green proteins), and by stimulating expression of the translation machinery (turquoise proteins). TORC1 inhibits catabolic process such as autophagy (dark red proteins), and blocks transcriptional stress responses mediated by Rtg1/3, Gln3, Msn2/4, and Ime1 (violet proteins). Some TORC1 readouts are also influenced by the protein kinase A (PKA) signalling pathway and Sch9 (red proteins). Gpr1 is a plasma membrane G protein coupled receptor (GPCR) that interacts with the heterotrimeric G protein α-subunit, Gpa2. Gpr1, Gpa2 and Ras2 sense nutritional signals and correspondingly regulate adenylyl cyclase (Cdc35) activity and consequently cAMP synthesis. TORC1 controls other readouts via type 2A (PP2A) and/or the PP2A-like protein phosphatase Sit4 (magenta proteins). TORC1 controls nuclear import and/or nuclear export of Sfp1 and Ime2. Arrows and bars denote positive and negative interactions, respectively. Solid arrows and bars refer to direct interactions, dashed arrows and bars refer to indirect and/or potential interactions. Red circles containing the letter P denote phosphorylated amino-acid residues. STRE, stress-responsive element; PDS, post-diauxic shift element; DAL, degradation of urea and allantoin; NDP, nitrogen discrimination pathway; RTG, retrograde regulation; TCA, tricarboxylic acid cycle; P bodies, processing bodies (i.e. discrete cytoplasmic foci to which mRNA is routed for degradation/storage).
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