[Lysosomal glycosidases and glycoproteinoses].

The development of chemicall, physical and enzymatic methods lead to the determination of numerous structures of glycoprotein glycans and allowed to classify them into "structural families". On the basis of this knowledge, it has been possible, 1) to demonstrate that the oligosaccharides and glycoasparagines accumulating in tissues and urines of patients with diseases characterized by a lack in lysosomal glycosidases originate from glycoprotein glycans incompletely catabolized; 2) to propose a scheme for the normal and pathological catabolism of glycoproteins and 3) to elucidate the problem of the origin of lysosomal glycosidases. These latter are internalized into the lysosomes either through a mechanism of secretion-reuptake, or by following an intracellular traffic, or via the cell plasma membrane. In al cases, membrane receptors intervene which specifically recognize phosphorylated oligomannosidic structures carried by the acidic hydrolases.