Isolation and Characterization of Phosphorylated Oligosaccharides from α‐N‐Acetylglucosaminidase that Are Recognized by Cell‐Surface Receptors

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  • KFKurt VON Figura
    Kurt VON Figura
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Abstract
Adsorptive endocytosis of lysosomal enzymes by fibroblasts and hepatocytes involves binding to cell surface receptors that recognize on lysosomal enzymes a phosphorylated carbohydrate, most likely a mannose 6‐phosphate residue [Kaplan et al. (1977) Proc. Natl Acad. Sci. U.S.A. 74, 2026–2030; Ullrich et al. (1978) Hoppe‐Seyler's Z. Physiol. Chem. 359, 1591–1598]. Loss of α‐N‐acetylglucosaminidase endocytosis after treatment with endoglucosaminidase H indicated that the recognition site of α‐N‐acetylglucosaminidase is located on N‐glycosidically linked oligosaccharides of the high mannose type. Acidic oligosacchrides with an average molecular weight of 2200 were liberated from α‐N‐acetylglucosaminidase by endoglucosaminidase H. These oligosaccharides were susceptible to degradation by alkaline phosphatase, α‐mannosidase and β‐N‐acetylglucosaminidase. At the non‐reducing terminal these oligosaccharides bear phosphorylated mannose and/or N‐acetylglucosamine residues.

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