Light and heavy lysosomes: characterization of N-acetyl-beta-D-hexosaminidase isolated from normal and I-cell disease lymphoblasts
| Autor: | Darin L. Wright, Michael Jenks, Richard Y. Yeh, Valerie Norton, A L Miller, Robin Robertson |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Adult
Glycoside Hydrolases Neuraminidase Cell Fractionation Endoplasmic Reticulum Biochemistry Chromatography Affinity chemistry.chemical_compound Mucolipidoses Lectins medicine Humans Hexosaminidase Lymphocytes Child Cells Cultured chemistry.chemical_classification Chemistry Oligosaccharide medicine.disease Hematopoietic Stem Cells Molecular biology beta-N-Acetylhexosaminidases Enzyme Hexosaminidases Galactose Specific activity I-cell disease Cell fractionation Plant Lectins Lysosomes Intracellular |
| Zdroj: | Glycobiology. 3(4) |
| ISSN: | 0959-6658 |
| Popis: | We previously reported that I-cell disease lymphoblasts maintain normal or near-normal intracellular levels of lysosomal enzymes, even though N-acetylglucosamine-1-phosphotransferase activity is severely depressed or absent (Little et al., Biochem. J., 248, 151-159, 1987). The present study, employing subcellular fractionation on colloidal silica gradients, indicates that both light and heavy lysosomes isolated from I-cell disease and pseudo-Hurler polydystrophy lymphoblasts possess normal specific activity levels of N-acetyl-beta-D-hexosaminidase, alpha-D-mannosidase and beta-D-glucuronidase. These current findings are in contrast to those of cultured fibroblasts from the same patients, where decreased intralysosomal enzyme activities are found. Column chromatography on Ricinus communis revealed that N-acetyl-beta-D-hexosaminidase in both heavy and light I-cell disease lysosomal fractions from lymphoblasts possesses an increased number of accessible galactose residues (30-50%) as compared to the enzyme from the corresponding normal controls. Endo-beta-N-acetylglucosaminidase H treatment of N-acetyl-beta-D-hexosaminidase from the I-cell lysosomal fractions suggests that the majority of newly synthesized high-mannose-type oligosaccharide chains are modified to complex-type carbohydrates prior to being transported to lysosomes. This result from lymphoblasts differs from previous findings with fibroblasts, where N-acetyl-beta-D-hexosaminidase from I-cell disease and pseudo-Hurler polydystrophy lysosomes exhibited properties associated with predominantly high-mannose-type oligosaccharide chains.(ABSTRACT TRUNCATED AT 250 WORDS) |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|