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

beta-D-Glucuronidase (EC 3.2.1.31) was purified to homogeneity from human spleen, and enzyme fractions from CM-Sephadex were examined for uptake by fibroblasts and retention by a column of immobilized phosphomannosyl receptor. Uptake and binding were enhanced by treatment of the enzyme with alpha-N-acetylglucosaminyl phosphodiesterase, greatly reduced by prior treatment with alkaline phosphatase, and restored by subsequent treatment with alpha-N-acetylglucosaminyl phosphodiesterase. Immobilized phosphomannosyl receptor was used to separate high and low uptake enzyme forms. About 25% of the total beta-glucuronidase was retained by the receptor column and eluted with mannose 6-phosphate. The rate of uptake of retained enzyme was 2.5-3.0-fold greater than that of the enzyme applied to the receptor column. The fraction retained by the column was reduced to 5-10% by prior treatment of the enzyme with alkaline phosphatase. This phosphatase-resistant, receptor-retained fraction was taken up at only 24% the rate of non-phosphatase-treated, receptor-retained enzyme. However, its uptake was increased 7-fold by treatment with alpha-N-acetylglucosaminyl phosphodiesterase. The enhanced rate of pinocytosis conferred by treatment of the enzyme with alpha-N-acetylglucosaminyl phosphodiesterase was destroyed by a subsequent treatment with alkaline phosphatase. These studies demonstrate that although most of the "high uptake" enzyme in beta-glucuronidase from human spleen binds to receptors through phosphomonoesters of mannose, a significant fraction can interact with immobilized phosphomannosyl receptor and be taken up by fibroblasts through interactions involving mannose 6-phosphate in diester linkage with N-acetyl-D-glucosamine.
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PMID:Human beta-glucuronidase pinocytosis and binding to the immobilized phosphomannosyl receptor. Effects of treatment of the enzyme with alpha-N-acetylglucosaminyl phosphodiesterase. 630 37