ULK1, phosphorylated (Ser555) (Serine/Threonine-protein Kinase ULK1, Unc-51-like Kinase 1, KIAA0722)

Two related serine/threonine kinases, UNC- 51-like kinase -1 and -2 (ULK1, ULK2), were discovered as mammalian homologs of the C. elegans gene UNC-51 in which mutants exhibited abnormal axonal extension and growth (1-4). Both proteins are widely expressed and contain an amino terminal kinase domain followed by a central proline/serine rich domain and a highly conserved carboxy-terminal domain (CTD). The roles of ULK1 and ULK2 in axon growth have been linked to studies showing that the kinases are localized to neuronal growth cones and are involved in endocytosis of critical growth factors such as NGF (5). Yeast two-hybrid studies found ULK1/2 associated with modulators of the endocytic pathway, SynGap, and syntenin (6). Structural similarity of ULK1/2 has also been recognized with the yeast autophagy protein Atg1/Apg1 (7). Knockdown experiments using siRNA demonstrated that ULK1 is essential for autophagy (8), a catabolic process for the degradation of bulk cytoplasmic contents (9,10). It appears that Atg1/ULK1 can act as a convergence point for multiple signals that control autophagy (11), and can bind to several autophagy-related (Atg) proteins, regulating phosphorylation states and protein trafficking (12-16). Phosphorylation of ULK1 by AMPK at Ser555 is critical for starvation-induced autophagy, cell survival under conditions of low nutrients and energy, and mitochondiral homeostasis (17). Applications: Suitable for use in Western Blot and Immunoprecipitation. Other applications not tested. Recommended Dilution: Western Blot: 1:1000 Immunoprecipitation: 1:100 Optimal dilutions to be determined by the researcher. Storage and Stability: May be stored at 4 degrees C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Aliquots are stable for at least 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.