Pleiotropic mutations of lysosomal function in human patients and in Chinese hamster ovary cells

The biosynthesis of lysosomal enzymes entails a complex series of events. The nascent proteins enter the endoplasmic reticulum for glycosylation. Phosphorylation of the enzymes subsequently occurs in the Golgi area. Equipped with a phosphomannose recognition marker, the enzymes are bound to specific receptors and translocated to lysosomes. Mutations are known in the following steps: early glycosylation (CHO cells), phosphorylation (patients with I-cell disease and pseudo-Hurler polydystrophy), and receptor binding (CHO cells).