title: Recognition of human urine alpha-N-acetylglucosaminidase by rat hepatocytes. Involvement of receptors specific for galactose, mannose 6-phosphate and mannose.
abstract: 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.
mesh_terms: D000118:Acetylglucosaminidase / Q000652:urine*; D000469:Alkaline Phosphatase / Q000494:pharmacology; D000818:Animals; D004705:Endocytosis / Q000187:drug effects; D005260:Female; D005690:Galactose / Q000378:metabolism; D006596:Hexosaminidases / Q000652:urine*; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000201:enzymology*; D008358:Mannose / Q000378:metabolism; D008360:Mannosephosphates / Q000378:metabolism; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D009439:Neuraminidase / Q000494:pharmacology; D051381:Rats; D011955:Receptors, Drug / Q000378:metabolism*; D001616:beta-Galactosidase / Q000494:pharmacology
chemical_list: D008360:Mannosephosphates; D011955:Receptors, Drug; D000469:Alkaline Phosphatase; D006596:Hexosaminidases; D009439:Neuraminidase; D001616:beta-Galactosidase; D000118:Acetylglucosaminidase; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D008358:Mannose; D005690:Galactose