| Background |
SMG-1 is a member of the phosphoinositide 3-kinase-related kinase (PIKK) family, which includes ATM, ATR, mTOR, DNA-PKcs, and TRRAP Activated by DNA damage, SMG-1 has been shown to phosphorylate p53 and hUpf1 (SMG-2) hUpf1 is a subunit of the surveillance complex that allows degradation of messenger RNA species containing premature termination codons (PTCs). This process, known as nonsense-mediated mRNA decay (NMD), prevents the translation of truncated forms of proteins that may result in gain of function or dominant negative species. NMD occurs under normal cellular conditions as well as in response to damage SMG-1 has also been shown to affect cell death receptor signaling and to protect cells from extrinsically induced apoptotic cell death.
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