Involved in DNA damage response; activates kinases ATM, SMC1A and PRKDC by modulating their phosphorylation status following ionizing radiation (IR) stress. Plays a role in regulating mitochondrial function and cell proliferation (By similarity). Required for protein stability of MTOR and MTOR-related proteins, and cell cycle progress by growth factors (PubMed:25657994). Interacts with BRCA1 and ATM. Interacts with MTOR, RPTOR, NDFIP1, SMC1A and PRKDC. Present at double strand breaks (DSBs) following ionizing radiation treatment (By similarity). The ubiquitinated form localizes in the nucleus in a NDFIP1-dependent manner. High levels detected in the cortex and much lower levels detected in the cerebellum, spinal cord and lung (at protein level). Ubiquitinated by NEDD4, NEDD4L and ITCH; mono- and polyubiquitinated forms are detected. Extended N-terminus.