ULK1

Description

The ULK1 (unc-51 like autophagy activating kinase 1) is a protein-coding gene located on chromosome 12.

Serine/threonine-protein kinase ULK1 is an enzyme that in humans is encoded by the ULK1 gene. Unc-51-like autophagy-activating kinases 1 and 2 (ULK1/2) are two similar isoforms of an enzyme that in humans is encoded by the ULK1/2 genes. The enzyme is specifically a kinase that is involved with autophagy, particularly in response to amino acid withdrawal. Not many studies have been done comparing the two isoforms, but some differences have been recorded.

== Function == Ulk1/2 is an important protein in autophagy for mammalian cells, and is homologous to ATG1 in yeast. It is part of the ULK1-complex, which is needed in early steps of autophagosome biogenesis. The ULK1 complex also consists of the FAK family kinase interacting protein of 200 kDa (FIP200 or RB1CC1) and the HORMA (Hop/Rev7/Mad2) domain-containing proteins ATG13 and ATG101. ULK1, specifically, appears to be the most essential for autophagy and is activated under conditions of nutrient deprivation by several upstream signals which is followed by the initiation of autophagy. However, ULK1 and ULK2 show high functional redundancy; studies have shown that ULK2 can compensate for the loss of ULK1. Nutrient dependent autophagy is only fully inhibited if both ULK1 and ULK2 are knocked out.

Serine/threonine-protein kinase involved in autophagy in response to starvation (PubMed:18936157, PubMed:21460634, PubMed:21795849, PubMed:23524951, PubMed:25040165, PubMed:31123703, PubMed:29487085). Acts upstream of phosphatidylinositol 3-kinase PIK3C3 to regulate the formation of autophagophores, the precursors of autophagosomes (PubMed:18936157, PubMed:21460634, PubMed:21795849, PubMed:25040165). Part of regulatory feedback loops in autophagy: acts both as a downstream effector and negative regulator of mammalian target of rapamycin complex 1 (mTORC1) via interaction with RPTOR (PubMed:21795849). Activated via phosphorylation by AMPK and also acts as a regulator of AMPK by mediating phosphorylation of AMPK subunits PRKAA1, PRKAB2 and PRKAG1, leading to negatively regulate AMPK activity (PubMed:21460634). May phosphorylate ATG13/KIAA0652 and RPTOR; however such data need additional evidences (PubMed:18936157). Plays a role early in neuronal differentiation and is required for granule cell axon formation (PubMed:11146101). Also phosphorylates SESN2 and SQSTM1 to regulate autophagy (PubMed:25040165, PubMed:37306101). Phosphorylates FLCN, promoting autophagy (PubMed:25126726). Phosphorylates AMBRA1 in response to autophagy induction, releasing AMBRA1 from the cytoskeletal docking site to induce autophagosome nucleation (PubMed:20921139). Phosphorylates ATG4B, leading to inhibit autophagy by decreasing both proteolytic activation and delipidation activities of ATG4B (PubMed:28821708). {ECO:0000269|PubMed:11146101, ECO:0000269|PubMed:18936157, ECO:0000269|PubMed:20921139, ECO:0000269|PubMed:21460634, ECO:0000269|PubMed:21795849, ECO:0000269|PubMed:23524951, ECO:0000269|PubMed:25040165, ECO:0000269|PubMed:25126726, ECO:0000269|PubMed:28821708, ECO:0000269|PubMed:29487085, ECO:0000269|PubMed:31123703, ECO:0000269|PubMed:37306101}.

ULK1 is also known as ATG1, ATG1A, UNC51, Unc51.1, hATG1.

Associated Diseases

WES Whole Exome Sequencing