Membrane-bound N-acetyl-beta-glucosaminidase. Different binding specificity in control and I-cell disease livers.
Several lysosomal enzymes solubilized at pH 4 from saponin-treated membranes showed markedly variable affinities to the bovine liver phosphomannosyl receptor in both bovine and human livers. The enzymes from I-cell disease liver did not bind the receptor in spite of normal intracellular activities. N-Acetyl-beta-glucosaminidase was effectively released from the membrane preparation of a control liver by mannose 6-phosphate, and other sugars showed little effect in this experiment. However, in the I-cell disease liver, dissociation occurred not by mannose 6-phosphate but by other sugars, such as fucose, mannose and N-acetyl-D-glucosamine. These results indicate the presence of an alternate transport system other than the pathway mediated by the mannose 6-phosphate receptor, and the role of other sugar-binding proteins is discussed in intracellular processing and transport of newly synthesized enzymes.
D000118:Acetylglucosaminidase / Q000378:metabolism*; D000818:Animals; D002241:Carbohydrates / Q000494:pharmacology; D002417:Cattle; D002462:Cell Membrane / Q000201:enzymology; D006596:Hexosaminidases / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007223:Infant; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D009081:Mucolipidoses / Q000201:enzymology*; D011485:Protein Binding / Q000187:drug effects; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D012995:Solubility
D002241:Carbohydrates; D017527:Receptor, IGF Type 2; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; C034304:cation-dependent mannose-6-phosphate receptor; D006596:Hexosaminidases; D000118:Acetylglucosaminidase