The left panel shows major steps in the biosynthesis, processing, and maturation of N-linked glycan chains (from ref. 4), and the right panel shows the selective phosphorylation of N-glycans on lysosomal enzymes, with mediates their selective targeting to lysosomes, via mannose 6-phosphate receptors (from ref. 7). Man, mannose; GlcNAc, N-acetylglucosamine; Glc, glucose; Gal, galactose; Fuc, fucose; Sia, sialic acid.