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Molecular defect in processing alpha-fucosidase in fucosidosis
Biochemical and Biophysical Research Communications
|November 27, 1985
Summary
Alpha-L-fucosidase is processed from a 53,000-dalton precursor to a 50,000-dalton mature form in human skin fibroblasts. This study reveals molecular defects in fucosidosis patients, with most synthesizing no detectable alpha-L-fucosidase protein.
Area of Science:
- Biochemistry
- Cell Biology
- Genetics
Background:
- Alpha-L-fucosidase is an enzyme crucial for cellular processes.
- Understanding its processing and molecular defects is vital for genetic disorder research.
Purpose of the Study:
- To investigate the processing of alpha-L-fucosidase in normal human skin fibroblasts.
- To identify the molecular basis of alpha-L-fucosidase deficiency in fucosidosis patients.
Main Methods:
- Pulse-chase labeling with [35S]methionine followed by immunoprecipitation with an alpha-L-fucosidase antibody.
- Enzymatic treatment with Endoglycosidase-H to analyze oligosaccharide units.
- Tunicamycin pretreatment to assess N-linked glycosylation.
- Analysis of fibroblast cultures from fucosidosis patients.
Main Results:
- Normal fibroblasts process an enzymatically active 53,000-dalton alpha-L-fucosidase precursor to a 50,000-dalton mature form.
- Endoglycosidase-H treatment confirmed the removal of a single N-linked oligosaccharide unit during processing.
- Fibroblasts from 8 out of 11 fucosidosis patients showed no detectable alpha-L-fucosidase protein.
- Two patients synthesized the precursor but not the mature form, indicating a processing defect.
Conclusions:
- This study provides the first evidence of alpha-L-fucosidase processing in cells.
- It presents precise molecular evidence of defects in fucosidosis, a lysosomal storage disorder.