QL-IX-55 is a selective ATP-competitive inhibitor of mTORC1/2 with IC50s of 50/50/10-50 nM for Human mTORC1/Yeast mTORC1/Yeast mTORC2, respectively. IC50 value: 50/50/10-50 nM (Human mTORC1/Yeast mTORC1/Yeast mTORC2) Target: mTORC1/2 The functional target of QL-IX-55 is the ATP-binding site of TOR2 as evidenced by the discovery of resistant alleles of TOR2 through rational design and unbiased selection strategies. QL-IX-55 is capable of potently inhibiting both TOR complex 1 and 2 (TORC1 and TORC2) as demonstrated by biochem. IP kinase assays (IC50 <50 nM) and cellular assays for inhibition of substrate YPK1 phosphorylation. In contrast to rapamycin, QL-IX-55 is capable of inhibiting TORC2-dependent transcription, which suggests that this compd. will be a powerful probe to dissect the Tor2/TORC2-related signaling pathway in yeast.