Quantitative Phosphoproteomics Reveal mTORC1 Activates de Novo Pyrimidine Synthesis

Coordinating Metabolism Growth factors help to coordinate metabolism with growth in part by stimulating the activity of the protein kinase mTORC1 (mechanistic target of rapamycin complex 1). Ben-Sahra et al. (p. 1323 , published online 21 February) and Robitaille et al. (p. 1320 , published online 21 February) independently identified a key target of mTORC1—carbamolyl-phosphate synthase 2, or CAD, the rate-limiting enzyme for de novo synthesis of pyrimidines. Metabolomic profiling and phosphoproteomic analyses of normal cells and cells lacking signaling by mTORC1 converged on CAD as a key point at which growth-promoting signals also ramp up production of nucleic acids.