Regulator of the DNA damage response (DDR). Part of the TTT complex that is required to stabilize protein levels of the phosphatidylinositol 3-kinase-related protein kinase (PIKK) family proteins. The TTT complex is involved in the cellular resistance to DNA damage stresses, like ionizing radiation (IR), ultraviolet (UV) and mitomycin C (MMC). Together with the TTT complex and HSP90 may participate in the proper folding of newly synthesized PIKKs. Promotes assembly, stabilizes and maintains the activity of mTORC1 and mTORC2 complexes, which regulate cell growth and survival in response to nutrient and hormonal signals. May be involved in telomere length regulation (By similarity). Component of the TTT complex composed of TELO2, TTI1 and TTI2. Interacts with ATM, ATR, MTOR, PRKDC, RUVBL2, TTI1, TTI2, SMG1 and TRRAP. Component of the mTORC1 and mTORC2 complexes. Interacts (phosphorylated form) with PIH1D1 (PubMed:24794838). Interaction with PIH1D1 mediates interaction of TELO2 with the R2TP complex composed of RUVBL1, RUVBL2, PIH1D1, and RPAP3 (By similarity). Hydroxylation by PHD3 is required for a proper interaction with ATR, and activation of the ATR/CHK1/p53 pathway following DNA damage. Phosphorylated at Ser-486 by CK2 following growth factor deprivation, leading to its subsequent ubiquitination by the SCF(FBXO9) complex. Phosphorylation by CK2 only takes place when TELO2 is bound to mTORC1, not mTORC2; leading to selective ubiquitination of mTORC1-associated protein (By similarity). Ubiquitinated by the SCF(FBXO9) complex following phosphorylation by CK2 in response to growth factor deprivation, leading to its degradation by the proteasome. Only mTORC1-associated protein is ubiquitinated and degraded, leading to selective inactivation of mTORC1 to restrain cell growth and protein translation, while mTORC2 is activated due to the relief of feedback inhibition by mTORC1 (By similarity). Belongs to the TEL2 family. Truncated C-terminus.