Serine/threonine-protein kinase SMG1 is a phosphatidylinositol kinase-related protein that acts as an mRNA-surveillance protein and is a key component of nonsense-mediated decay (NMD) [, , , ]. In C.elegans, SMG1 is a key regulator of growth. Loss of SMG1 leads to hyperactive responses to injury and subsequent growth that continues out of control. It has an antagonistic role to mTOR signalling in worms []and possibly also in higher eukaryotes.
Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism that detects and degrades mRNAs containing premature translation termination codons. Protein SMG9 is a component of the SMG1C protein kinase complex (along with SMG1 and SMG8) which is recruited to stalled ribosomes. SMG8 and SMG9 suppress SMG1 kinase activity in the isolated SMG1 complex [].
This entry represents the N-terminal domain of SMG1, which is a member of the phosphoinositide 3 kinase-like kinase (PIKK) family. SMG1 associates with components of the mRNA surveillance complex and is involved in the regulation of nonsense-mediated mRNA decay []. It also plays an important role in genotoxic stress responses to DNA damage [].
