Acts as a regulator of autophagy in response to S.aureus infection by promoting activation of LC3 (MAP1LC3A, MAP1LC3B or MAP1LC3C). Acts by interacting with ATG16L1, leading to promote a functional complex between LC3 and ATG16L1 and promoting LC3 lipidation and subsequent activation of autophagy (PubMed:27273576, PubMed:23376921). Modulates the O-glycosylation and complex N-glycosylation steps occurring during the Golgi maturation of several proteins such as APP, BACE1, SEAP or PRNP (PubMed:20427278). Inhibits APP transport to the cell surface and further shedding (PubMed:20427278). Interacts with ATG16L1 (via WD repeats). Mainly localizes to late endosomes/lysosomes. Probably first exported to the cell surface and then actively endocytosed to transiently localize in early endosomes on its way to the late endosomal/lysosomal compartment where it becomes quickly degraded. The ATG16L1-binding motif mediates interaction with ATG16L1 and promotes autophagy. N-glycosylated. Belongs to the TMEM59 family. Truncated N-terminus.