May function as an intracellular leucine sensor that negatively regulates the TORC1 signaling pathway (PubMed:25263562). May also regulate the insulin-receptor signaling pathway through activation of TORC2 (By similarity). This metabolic regulator may also play a role in protection against oxidative and genotoxic stresses (By similarity). May prevent the accumulation of reactive oxygen species (ROS) through the alkylhydroperoxide reductase activity born by the N-terminal domain of the protein (By similarity). {ECO:0000250|UniProtKB:P58004, ECO:0000250|UniProtKB:Q9CYP7, ECO:0000269|PubMed:25263562}. This is the function of Ensembl gene identifier ENSG00000149212 (SESN3, sestrin 3).