Phosphatidylinositol 3-kinase homolog, component of TORC1, which regulates multiple cellular processes to control cell growth in response to environmental signals. TORC1 controls the switch between cell proliferation and differentiation by sensing nutrient availability. Nutrient limitation and environmental stress signals cause inactivation of TORC1. Active TORC1 positively controls cell growth and ribosome biogenesis by regulating ribosomal protein gene expression (PubMed:17121544, PubMed:17179073, PubMed:17261596). In nutrient rich conditions, responsible for the phosphorylation of AGC S6 kinase (S6K) psk1 at 'Thr-392' and 'Thr-415', activating psk1 kinase activity and promoting phosphorylation of ribosomal protein S6. Also catalyzes the nutrient-dependent phosphorylation of sck1 and sck2 (PubMed:20144990, PubMed:22976295). TORC1 negatively controls G1 cell-cycle arrest, sexual development and amino acid uptake. Represses mating, meiosis and sporulation efficiency by interfering with the functions of the transcription factor ste11 and the meiosis-promoting RNA-binding protein mei2 (PubMed:17046992). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] The target of rapamycin complex 1 (TORC1) is composed of at least mip1, pop3/wat1, tco89, toc1 and tor2 (PubMed:17046992, PubMed:18076573, PubMed:17261596). Tor2 interacts with the small GTPase rhb1 (PubMed:17121544). Tor2 interacts with ste11 and mei2 (PubMed:17046992). Belongs to the PI3/PI4-kinase family.