Can convert Man(9)GlcNAc(2) and Man(8)GlcNAc(2) into N-glycans with a terminal alpha-1,6-linked Man residue in the C-branch. Functions in the formation of unique N-glycan structures that are specifically recognized by components of the endoplasmic reticulum-associated degradation (ERAD) machinery, which leads to the degradation of misfolded glycoproteins. Most likely generates N-glycan signal on misfolded glycoproteins that is subsequently recognized by OS9. Required for ERAD of the heavily glycosylated and misfolded BRI1 variants BRI1-5 and BRI1-9. Does not seem to play role in N-glycan processing of correctly folded proteins destined for secretion. Protein modification; protein glycosylation. Belongs to the glycosyl hydrolase 47 family.