Phosphatidylinositol 3-kinase homolog, component of TORC1, which regulates multiple cellular processes to control cell growth in response to environmental signals (By similarity). Nutrient limitation and environmental stress signals cause inactivation of TORC1 (PubMed:28993463). Active TORC1 positively controls ribosome biogenesis via control of rRNA, ribosomal protein and tRNA gene expression, and rRNA processing. TORC1 positively controls protein biosynthesis by regulation of mRNA stability, translation initiation factor activity, and high-affinity amino acid permeases that serve to provide amino acids for use by the translation machinery. TORC1 also promotes growth by sequestering a number of nutrient and general stress-responsive transcription factors in the cytoplasm. TORC1 negatively controls macroautophagy, a process to recycle surplus cytoplasmic mass under nutrient starvation conditions. TORC1 controls many of these processes via TIP41-TAP42-mediated inhibition of the type 2A-related phosphatases PP2A and SIT4 (By similarity). In nutrient-rich conditions, responsible for the phosphorylation of AGC S6 kinase (S6K) YPK3, activating YPK3 kinase activity and promoting phosphorylation of ribosomal protein S6. Phosphorylates kinase SCH9 at 6 amino acids in the C-terminus, activating SCH9 kinase activity to properly regulate ribosome biogenesis, translation initiation, and entry into stationary phase (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by the glutamine sensor PIB2 in nutrient-rich conditions. The target of rapamycin complex 1 (TORC1) is composed of at least KOG1, LST8, TCO89 and either TOR1 (TORC1-A) or TOR2 (TORC1-B) (By similarity). Interacts with PIB2; following activation of PIB2 by glutamine or cysteine (By similarity). TORC1 binds to and is inhibited by FKBP-rapamycin (By similarity). Also localizes to membranous structures both proximal to, yet distinct from, the plasma membrane as well as within the cell interior, probably endosomal or Golgi membranes (By similarity). Localization to the vacuolar membrane is dependent upon PIB2 and GTR1 (PubMed:28993463). Belongs to the PI3/PI4-kinase family.