Fig. 3
From: Muscle stem cell adaptations to cellular and environmental stress
The mTORC1 pathway in stress. The presence of growth factors (grey, green, purple circles), abundant amino acids (brown diamonds), and cellular energy (light brown mitochondria) positively regulated mTORC1 to regulate cell growth pathways through the phosphorylation of S6K1 kinase (green arrow), and cell proliferation pathways (red arrow) through the phosphorylation of eIF4E binding protein (4E-BP). Phosphorylated 4E-BP no longer competes for eIF4E binding, permitted eIF4E to initiate cap-dependent translation. eIF4E is the cap binding protein that functions within the eIF4F tertiary complex (purple) along with eIF4G and eIF4A (not shown). Cellular and environmental stress activates the TSC1/TSC2 complex to inhibit mTORC1 signalling, leading to the repression of these pathways, with consequent decrease in cell growth and proliferation