Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adsorptive endocytosis of alpha-N-acetylglucosaminidase from human urine by isolated rat hepatocytes is inhibited by glycoproteins, polysaccharides and sugars that are known to bind to cell-surface receptors specific for either terminal galactose/N-acetylgalactosamine residues, terminal mannose residues or mannose 6-phosphate residues. Recognition of alpha-N-acetylglucosaminidase by a cell-surface receptor specific for terminal galactose/N-acetylgalactosamine residues is supported by the observations (a) that neuraminidase pretreatment of the enzyme enhances endocytosis, (b) that beta-galactosidase treatment decreases endocytosis and (c) that neuraminidase pretreatment of hepatocytes decreases alpha-N-acetylglucosaminidase endocytosis. Recognition of alpha-N-acetylglucosaminidase via receptors recognizing mannose 6-phosphate residues is lost after treatment of the enzyme with alkaline phosphatase and endoglucosaminidase H. The effect of endoglucosaminidase H supports the view that the mannose 6-phosphate residues reside in N-glycosidically linked oligosaccharide side chains of the high-mannose type. The weak inhibition of endocytosis produced by compounds known to interact with cell-surface receptors specific for mannose residues suggests that this recognition system plays only a minor role in the endocytosis of lysosomal alpha-N-acetylglucosaminidase by hepatocytes.
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PMID:Recognition of human urine alpha-N-acetylglucosaminidase by rat hepatocytes. Involvement of receptors specific for galactose, mannose 6-phosphate and mannose. 11 70

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 alpha-N-acetylglucosaminidase endocytosis after treatment with endoglucosaminidase H indicated that the recognition site of alpha-N-acetylglucosaminidase is located on N-glycosidically linked oligosaccharides of the high mannose type. Acidic oligosaccharides with an average molecular weight of 2200 were liberated from alpha-N-acetylglucosaminidase by endoglucosaminidase H. These oligosaccharides were susceptible to degradation by alkaline phosphatase, alpha-mannosidase and beta-N-acetylglucosaminidase. At the non-reducing terminal these oligosaccharides bear phosphorylated mannose and/or N-acetylglucosamine residues.
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PMID:Isolation and characterization of phosphorylated oligosaccharides from alpha-N-acetylglucosaminidase that are recognized by cell-surface receptors. 42 91

Receptor-mediated endocytosis of alpha-N-acetylglucosaminidase by cultured epithelial rat liver cells is inhibited by mannose, L-fucose and most effectively by mannose 6-phosphate. Endocytosis of alpha-N-acetylglucosaminidase is lost after treatment of the enzyme with alkaline phosphatase. These findings indicate that epithelial rat liver cells possess cell surface receptors that recognize a phosphorylated carbohydrate on alpha-N-acetylglucosaminidase, as was previously reported for cell surface receptors of human skin fibroblasts. Inhibition of alpha-mannosidase endocytosis by epithelial rat liver cells in the presence of mannose 6-phosphate and loss of enzyme endocytosis after treatment with alkaline phosphatase suggest that this enzyme is recognized by the same receptor.
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PMID:Epithelial rat liver cells have cell surface receptors recognizing a phosphorylated carbohydrate on lysosomal enzymes. 56 30

Adsorptive endocytosis of five different lysosomal enzymes from various human and non-human sources was susceptible to inhibition by mannose and l-fucose, methyl alpha-d-mannoside, alpha-anomeric p-nitrophenyl glycosides of mannose and l-fucose, mannose 6-phosphate and fructose 1-phosphate. A few exceptions from this general scheme were observed for particular enzymes, particularly for beta-glucuronidase from human urine. The inhibition of alpha-N-acetylglucosaminidase endocytosis by mannose, p-nitrophenyl alpha-d-mannoside and mannose 6-phosphate was shown to be competitive. The loss of endocytosis after alkaline phosphatase treatment of lysosomal enzymes supports the hypothesis that the phosphorylated sugars compete with a phosphorylated carbohydrate on the enzymes for binding to the cell-surface receptors [Kaplan, Achord & Sly (1977) Proc. Natl. Acad. Sci. U.S.A.74, 2026-2030]. Endocytosis of ;low-uptake' forms of alpha-N-acetylglucosaminidase and alpha-mannosidase was likewise susceptible to inhibition by sugar phosphates and by alkaline phosphatase treatment, suggesting that ;low-uptake' forms are either contaminated with ;high-uptake' forms or are internalized via the same route as ;high-uptake' forms. The existence of an alternative route for adsorptive endocytosis of lysosomal enzymes is indicated by the unaffected adsorptive endocytosis of rat liver beta-glucuronidase in the presence of phosphorylated sugars and after treatment with alkaline phosphatase.
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PMID:Evidence for lysosomal enzyme recognition by human fibroblasts via a phosphorylated carbohydrate moiety. 64 6