title: Endocytotic internalization of alpha-2-macroglobulin: alpha-galactosidase conjugate by cultured fibroblasts derived from Fabry hemizygote.
abstract: Endocytotic internalization of alpha-galactosidase by cultured fibroblasts derived from a patient with Fabry's disease was achieved via receptor-mediated endocytosis of alpha-2-macroglobulin (alpha-2-M). alpha-galactosidase of coffee beans was conjugated to alpha-2-M when the latter was treated with trypsin. Internalization of the conjugate resulted in an increase of alpha-galactosidase activity in the crude cell extracts. The observed internalization was blocked by the presence of bacitracin, an inhibitor of binding between alpha-2-M and its receptor on the cell surface. When the cells were incubated at 4 degrees C with the conjugate, internalization was also inhibited. The alpha-galactosidase activity in the cells was saturated when the concentration of the conjugate in the medium was 40 micrograms/ml. Since non-conjugated alpha-galactosidase was not effectively internalized, the observed internalization of the conjugate was mediated by recognition of alpha-2-M by its receptor. The effective internalization of alpha-galactosidase described in this paper has a potential use in the enzyme replacement therapy of Fabry's disease.
mesh_terms: D002478:Cells, Cultured; D003069:Coffee / Q000201:enzymology; D004705:Endocytosis; D000795:Fabry Disease / Q000201:enzymology* / Q000378:metabolism / Q000628:therapy; D005347:Fibroblasts / Q000378:metabolism; D005696:Galactosidases / Q000008:administration & dosage*; D006801:Humans; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism; D000519:alpha-Galactosidase / Q000008:administration & dosage*; D000511:alpha-Macroglobulins / Q000378:metabolism*
chemical_list: D003069:Coffee; D000511:alpha-Macroglobulins; D005696:Galactosidases; D000519:alpha-Galactosidase; D014357:Trypsin