The function of WDR59 (WD repeat domain 59, Ensembl gene identifier ENSG00000103091) is as follows. As a component of the GATOR2 complex, functions as an activator of the amino acid-sensing branch of the mTORC1 signaling pathway (PubMed:23723238, PubMed:25457612, PubMed:27487210, PubMed:35831510, PubMed:36528027, PubMed:36577058). The GATOR2 complex indirectly activates mTORC1 through the inhibition of the GATOR1 subcomplex (PubMed:23723238, PubMed:27487210, PubMed:35831510, PubMed:36528027). GATOR2 probably acts as an E3 ubiquitin-protein ligase toward GATOR1 (PubMed:36528027). In the presence of abundant amino acids, the GATOR2 complex mediates ubiquitination of the NPRL2 core component of the GATOR1 complex, leading to GATOR1 inactivation (PubMed:36528027). In the absence of amino acids, GATOR2 is inhibited, activating the GATOR1 complex (PubMed:25457612, PubMed:27487210). {ECO:0000269|PubMed:23723238, ECO:0000269|PubMed:25457612, ECO:0000269|PubMed:27487210, ECO:0000269|PubMed:35831510, ECO:0000269|PubMed:36528027, ECO:0000269|PubMed:36577058}.