Lysosomal Degradation of Glycoproteins

Rome, L.H. Hill, D.F. Lysosomal degradation of glycoproteins and glycosaminoglycans. Efflux and recycling of sulphate and N-acetylhexosamines. Biochemical J. 1986, 235, 707-713. 

Genetic defects in the degradation of glycoproteins are representative of lysosomal storage disorders. Each disease is caused by a deficiency of a lysosomal hydrolase, accumulation and urinary excretion of substrates, a progressive clinical course and considerable phenotypic variation. These disorders also manifest the clinical symptoms normally associated with genetic mucopolysaccharidoses, namely coarse facies, dysostosis multiplex and/or ocular involvement. 

Aronson NN Jr, Kuranda MJ (1989) Lysosomal degradation of Asn-linked glycoproteins. 

Aronson, N.N. Jr. Backes, M. Kuranda, M.J. Rat Liver Chitobiase Purification, Properties, and Role in the Lysosomal Degradation of Asn-Linked Glycoproteins. Arch. Biochem. Biophys. 1989, 272, 290-300. 

Swainsonine (1) is of great biochemical interest since it is a potent and specific inhibitor of both lysosomal a-mannosidase and mannosidase II, which are involved in the cellular degradation of polysaccharides and in the processing of asparagine-linked glycoproteins, respectively [1]. 

There are other lysosomal disorders in addition to those shown in Figure 9.20 and Table 9.1. For instance, several types of fucosidoses exist, which affect such structures as glycoproteins and blood group substances. Sialidoses also exist. However, lysosomal fucosidase and sialidase (neuraminidase) deficiencies do not affect the degradation of gangliosides. 

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