ERdj8 is a novel ER membrane protein that localizes to a meshwork-like ER subdomain with PIS and Atg proteins; it governs autophagosome size during formation, with overexpression enlarging autophagosomes (requiring the J and TRX domains) and ablation impairing engulfment of larger targets; the role is conserved in the C. elegans orthologue dnj-8.

Single-pass type IV ER membrane protein with an N-terminal J domain and a thioredoxin domain; regulates the size of autophagosomes during formation; J-domain (His-57) and thioredoxin (Cys-171/Cys-174) residues are required for the autophagosome-enlargement activity.

Records that DNAJC16's core biological process is established, but the direct molecular function behind that process has not been demonstrated.

Records the current GO curation boundary: no molecular-function annotation should be asserted until the HSP70/co-chaperone or redox activity is experimentally shown.