In the last step of the N-glycan precursor biosynthesis pathway, the mature N-glycan (Glc3Man9GlcNAc2) is removed from the dolichyl diphosphate (DOLDP) molecule upon which it has been synthesized and attached to a nascent protein. The released DOLDP molecule is de-phosphorylated by dolichyl diphosphatase 1 (DOLPP1) to dolichyl phosphate (DOLP). DOLP is thus salvaged and be used as substrate for the synthesis of another N-glycan oligosaccharide (Wedgwood & Strominger 1980).