Transport of newly synthesized arylsulfatase A to the lysosome via transferrin receptor-positive compartments.
We have studied the convergence of the biosynthetic lysosomal route marked by the newly synthesized lysosomal enzyme arylsulfatase A (ASA) with the endosomal/prelysosomal compartment in ASA overexpressing baby hamster kidney (BHK) cells. A monoclonal antibody against ASA conjugated to transferrin (Tf-alpha ASA) was used to load the endocytic pathway via the transferrin receptor. Subsequent internalization of [125I]labeled ASA and Tf-alpha ASA conjugates at 18 degrees C followed by rewarming to 37 degrees C showed that immunocomplexes were formed within the recycling pathway and released into the medium. Furthermore, in cells labeled with [35S]methionine for 10 min about 54% of newly synthesized ASA passed into Tf-alpha ASA accessible compartments during a 4 hour chase period and accumulated in the medium. These data indicate that in overexpressing BHK cells the majority of newly synthesized ASA is transported to the lysosome via transferrin receptor-containing early endosomes.
Diesner
F
F
Georg-August-Universität, Biochemie II, Göttingen, Germany.
Sommerlade
H J
HJ
Braulke
T
T
D000818:Animals; D001692:Biological Transport; D002451:Cell Compartmentation / Q000502:physiology*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002553:Cerebroside-Sulfatase / Q000276:immunology / Q000378:metabolism*; D006224:Cricetinae; D004705:Endocytosis / Q000502:physiology*; D007425:Intracellular Membranes / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D011990:Receptors, Transferrin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
D011990:Receptors, Transferrin; D011994:Recombinant Proteins; D002553:Cerebroside-Sulfatase