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Catalytic domain of the Serine/Threonine kinase, Unc-51-like kinase 1 STKs catalyze the transfer of the gamma-phosphoryl group from ATP to serine/threonine residues on protein substrates. The ATG1/ULK complex is conserved from yeast to humans and it plays a critical role in the initiation of autophagy, the intracellular system that leads to the lysosomal degradation of cellular components and their recycling into basic metabolic units. ULK1 is required for efficient amino acid starvation-induced autophagy and mitochondrial clearance. It associates with three autophagy-related proteins (Atg13, FIP200 amd Atg101) to form the ULK1 complex. All fours proteins are essential for autophagosome formation. ULK1 is regulated by both mammalian target-of rapamycin complex 1 (mTORC1) and AMP-activated protein kinase (AMPK). mTORC1 negatively regulates the ULK1 complex in a nutrient-dependent manner while AMPK stimulates autophagy by inhibiting mTORC1. ULK1 also plays neuron-specific roles and is involved in non-clathrin-coated endocytosis in growth cones, filopodia extension, neurite extension, and axon branching. The ULK1 subfamily is part of a larger superfamily that includes the catalytic domains of other protein STKs, protein tyrosine kinases, RIO kinases, aminoglycoside phosphotransferase, choline kinase, and phosphoinositide 3-kinase. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",