Fig. 1

Mannose-6-phosphate (M6P) residues on the oligosaccharide chains of lysosomal enzymes are recognized by specific receptors present in the cell. Thanks to these receptors, the neo-synthesized enzymes are directed to the lysosomal compartment, where they perform their function. The M6P receptors are also expressed on the plasmatic membrane and this allows recombinant lysosomal enzymes to be “captured” by the cells and, following the pathway of the endocytic pathway, to be properly transported to the lysosome. Once lysosomes are reached, recombinant enzymes can replace the enzymatic deficit and degrade the accumulated substrate