Component of TORC1 complex, which is an essential cell growth regulator that controls plant development. Acts through the phosphorylation of downstream effectors that are recruited by the binding partner RAPTOR. Acts by activating transcription, protein synthesis and ribosome biogenesis, and inhibiting mRNA degradation and autophagy. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Insensitive to inhibition by rapamycin. The target of rapamycin complex 1 (TORC1) is composed of at least RAPTOR, LST8 and TOR. Belongs to the PI3/PI4-kinase family. Truncated N-terminus.