ATG16 L1 plays an essential role in autophagy. It is a homooligomer ant interacts with ATG5. Part of either the minor and major complexes respectively composed of 4 sets of ATG12-ATG5 and ATG16L1 (400 kDa) or 8 sets of ATG12-ATG5 and ATG16L1 (800 kDa). APG16 L1 localises to the cytoplasm, in particularly to preautophagosomal structure (PAS) where it is involved in the membrane targeting of ATG5. There are 5 named isoforms produced by alternative splicing. Genetic variation within ATG16 L1 are associated with susceptibility to inflammatory bowel disease type 1.