Catalytic domain of the Serine/Threonine kinases, Unc-51-like kinases 1 and 2, and similar proteins
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. ULK2 is ubiquitously expressed and is essential in autophagy induction. ULK1 and ULK2 have unique and cell-type specific roles, but also display partially redundant roles in starvation-induced autophagy. They both display neuron-specific functions: ULK1 is involved in non-clathrin-coated endocytosis in growth cones, filopodia extension, and axon branching; ULK2 plays a role in axon development. The ULK1/2 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.
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