Promotes cell and tissue growth, maintains tissue homeostatis and controls responses to environmental stress and aging (PubMed:11069885, PubMed:11069888, PubMed:19211682, PubMed:19225150). Regulates growth during animal development by coupling growth factor signaling to nutrient availability (PubMed:11069888). Central regulators of autophagy (PubMed:18604198, PubMed:19225150). May be involved in atg1 phosphorylation (PubMed:19225150). May also be involved, directly or indirectly, in the control of neuronal function (PubMed:15454083). Phosphorylates S6K/p70S6K, in vitro (PubMed:11069888). May regulate the activity of S6K (PubMed:11069885). Overexpression inhibits growth and reduces cell size (PubMed:14505573). Affects the timing of neuronal cell differentiation (PubMed:15454083). Hyperactivation of the signaling leads to accelerated differentiation, whereas inhibition of the signaling retards differentiation (PubMed:15454083). Thus, in addition to controlling growth of the cell in which it resides, it can also influence growth of distant cells and organs during development via a humoral mechanism (PubMed:14505573). As part of the TORC1 complex regulates energy homeostasis and promotes certain aspects of larval growth by negatively regulating REPTOR (PubMed:25920570). REPTOR functions downstream of TORC1 to regulate the expression of stress response genes in response to TORC1 inhibition resulting from nutrient deprivation (PubMed:25920570). When TORC1 activity is high it phosphorylates REPTOR which inhibits its recruitment into the nucleus and antagonizes their function (PubMed:25920570). This function is essential under normal feeding conditions to promote TORC1-dependent growth during larval development and, in adults and larvae to prevent the REPTOR-dependent expression of nutrient stress response genes (PubMed:25920570). In short, during development, it primarily controls growth, whereas in the adult, where there is relatively little growth, it controls aging and other aspects of nutrient-related physiology (PubMed:11069885, PubMed:11069888, PubMed:19211682, PubMed:19225150). Rag GTPases act as activators of TORC1 in response to amino acid signals (PubMed:18604198). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] May be part of a minimal complex, TORC1, consisting of tor, raptor and lst8. May be part of a minimal complex, TORC2, consisting of tor, rictor and lst8 (By similarity). Self-associates; assembles into homomultimeric complexes. Component of a multiprotein complex. By PI3K/Akt signaling, or by nutrients such as amino acids, and by high cellular energy levels. Not lethal. Displays phenotypes characteristic of amino acid deprivation, including reduced nucleolar size, lipid vesicle aggregation in the larval fat body, and a cell type-specific pattern of cell cycle arrest that can be bypassed by overexpression of the S-phase regulator cyclin E. Reach only the size of second instar larvae, at which point they undergo cell cycle arrest. Belongs to the PI3/PI4-kinase family.