Open AccessDephosphorylation of the Mannose‐6 Phosphate Recognition Marker is Localized in Late Compartments of the Endocytic Route
Author(s) -
Bresciani Roberto,
Figura Kurt
Publication year - 1996
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1996.0669w.x
Subject(s) - lysosome , endocytic cycle , dephosphorylation , mannose 6 phosphate , endosome , mannose 6 phosphate receptor , microbiology and biotechnology , endocytosis , acid phosphatase , mannose , biochemistry , phosphorylation , biology , compartment (ship) , phosphatase , chemistry , enzyme , cell , intracellular , receptor , growth factor , oceanography , geology
The mannose 6‐phosphate (Man6 P ) recognition marker in lysosomal proteins is known to be dephos‐phorylated after the delivery of lysosomal proteins to the endosome/lysosome compartment. The rate of Man6P recognition marker inactivation depends on the cell type and lysosomal protein. In the present study we show that in BHK 21 cells, which rapidly dephosphorylate lysosomal proteins, the recognition marker is stable in the endosomal compartment, to which lysosomal enzymes such as arylsulfatase A are delivered during endocytosis at 20°C. Dephosphorylation depends on the transfer of internalized lysosomal enzymes from the 20°C compartment to later compartments, most likely lysosomes. This transfer is sensitive to NH 4 Cl and nocodazole. In vitro experiments identified purple acid phosphatase (uteroferrin) as a candidate for the lysosomal phosphatase catalyzing in vivo the dephosphorylation of Man6 P recognition marker.