Targeting of phosphomannosyl-deficient arylsulfatase A to lysosomes of I-cell fibroblasts.
Fibroblasts from I-cell disease, a genetically-determined lysosomal storage disease, are shown to contain large amounts of phase-dense lysosomes. These lysosomes accumulated acridine orange and were specifically labeled with antibodies to arylsulfatase A. In normal skin fibroblasts the number of arylsulfatase-containing lysosomes was considerably lower. By immunocytochemistry, metabolic labeling and enzyme assay, the arylsulfatase A in I-cell fibroblasts was shown to be synthesized, stored and secreted at a level that was several-fold higher than that present in heterozygous I-cell or normal fibroblasts. Arylsulfatase A in I-cell fibroblasts differed from arylsulfatase in normal fibroblasts by the absence of endoglycosidase H-sensitive phosphorylated oligosaccharides. These findings indicate that arylsulfatase A in I-cells is targeted to lysosomes by a mechanism that does not appear to involve the phosphorylated mannose marker.
D002460:Cell Line; D002553:Cerebroside-Sulfatase / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D005347:Fibroblasts / Q000201:enzymology*; D006801:Humans; D008247:Lysosomes / Q000201:enzymology*; D009081:Mucolipidoses / Q000201:enzymology* / Q000473:pathology
D002553:Cerebroside-Sulfatase