※ ULK family introduction

    ULKs refer to Unc-51-like kinase which are classified into Others family. In vertebrates, at least five ULks have been found in this family and display a considerable homology to Atg1/UNC-51 in their kinase domain. Human ULK1 possesses an overall similarity of 41% to UNC-51.(1) ULK1 and ULK2 are the most closely related members of this family, sharing 78% homology of kinase domain and conserved C-terminal domain (CTD)(2). Studies show that ULK1 is critical to induce the autophagic response of cerebellar granule neurons to lowpatassium concentration in serum-free conditions.(1) ULK2 possesses the ability to compensate for the loss of ULK1 function in cell-type specific.(2) Overexpression of ULK3 is able to induce both autophagy and senescence in the human fibroblast cell line IMR90. (1)Another family member STK36 plays an important role in the sonic hedgehog pathway via regulating the activity of GLI transcription factors. Function of ULK4 remains more understood (1).

Reference
1. Alers, S., Loffler, A.S., Wesselborg, S. and Stork, B. (2012) The incredible ULKs . Cell Commun Signal, 10, 7. PMID: 22413737
2. Lee, E.J. and Tournier, C. (2011) The requirement of uncoordinated 51-like kinase 1 (ULK1) and ULK2 in the regulation of autophagy. Autophagy, 7, 689-695. PMID: 21460635