title: Molecular defect in processing alpha-fucosidase in fucosidosis.
abstract: In normal human skin fibroblasts, an enzymatically active 53,000-dalton form of alpha-fucosidase is processed to a 50,000-dalton mature form. Endoglycosidase-H treatment of [35S]methionine pulse-chase labelled material immunoprecipated with a polyclonal antibody to alpha-L-fucosidase (Andrews-Smith & Alhadeff, Biochim. Biophys. Acta 715: 90-96 (1982)) indicated the removal of a single N-linked oligosaccharide unit from both precursor and mature form of alpha-L-fucosidase. Tunicamycin pretreatment of normal fibroblasts indicated that no other N-linked oligosaccharide units were present. Studies on fibroblasts from patients with less than 5% of normal alpha-L-fucosidase activity (fucosidosis) showed 8 of 11 patients synthesized no detectable alpha-fucosidase protein whereas 2 synthesized normal amounts of 53,000 dalton precursor, none of the mature 50,000 dalton form was detectable and one contained small amounts of cross-reacting material. This is the first evidence for processing of alpha-L-fucosidase in cells and the first precise evidence of a molecular defect in fucosidosis.
mesh_terms: D002478:Cells, Cultured; D003429:Cross Reactions; D005347:Fibroblasts / Q000201:enzymology; D005645:Fucosidosis / Q000201:enzymology*; D006801:Humans; D008970:Molecular Weight; D009844:Oligosaccharides / Q000032:analysis; D012867:Skin / Q000201:enzymology; D005644:alpha-L-Fucosidase / Q000032:analysis / Q000096:biosynthesis* / Q000276:immunology
chemical_list: D009844:Oligosaccharides; D005644:alpha-L-Fucosidase