A rapid and efficient response to disturbances in nutrient levels is crucial for the survival of organisms from bacteria to humans.
Cells have therefore evolved a host of molecular pathways that can sense nutrient concentrations and quickly regulate gene expression and protein modification to respond to any changes.
AMP-activated kinase (AMPK) and mammalian target of rapamycin complex 1 serve as key molecules that sense cellular energy and nutrients levels, respectively.
The ratio of ATP to ADP and AMP is a barometer of cellular energy status and is therefore tightly monitored by the cell.
During glucose shortage, the energy sensor AMPK activates arginine methyltransferase CARM1 and mediates histone H3 hypermethylation (H3R17me2), leading to enhanced autophagy.
In addition, O-GlcNAc transferase (OGT) signals glucose availability to TET3 and inhibits TET3 by both decreasing its dioxygenase activity and promoting its nuclear export.
TOR receives information from levels of cellular amino acids and energy, and it regulates the activity of processes involved in cell growth, such as protein synthesis and autophagy.
Insulin-like signaling is the main mechanism of systemic nutrient sensing and mediates its growth-regulatory functions largely through the protein kinase pathway.
[13] In soil with low oxygen levels, ammonia is the primary nitrogen source, but toxicity is carefully controlled for with the transcription of ammonium transporters (AMTs).
[13] This is both a high and low affinity transceptor that senses varying concentrations of nitrate depending on its T101 residue phosphorylation.