Figure 1.

Summary of the multiple actions of MTORC1 that synergize to promote protein accumulation when nutrient supply and growth factors are high. Recent findings demonstrate the coordinate suppression of overall protein degradation by the ubiquitin-proteasome system as well as autophagy, which occur simultaneously with the enhancement of protein synthesis. Conversely, nutrient deprivation or MTOR inhibitors cause rapid increases in ubiquitination and overall proteolysis by these 2 systems as protein synthesis decreases.