Phosphorylation and subcellular location of {alpha}-L-fucosidase in Iymphoid cells from patients with I-cell disease and pseudo-Hurler polydystrophy |
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Authors: | DiCioccio Richard A; Miller Arnold L |
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Institution: | Department of Gynecologic Oncology, Roswell Park Cancer Institute Elm & Carlton Streets, Buffalo, NY 14263
1Department of Neurosciences, 0624, University of California, San Diego, School of Medicine La Jolla, CA 92093, USA |
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Abstract: | Mannose 6-phosphate is a recognition marker used by many newlymade acid hydrolases for their transport to lyso-somes. Previously,we investigated the incorporation of 32Pi into -L-fucosidaseof lymphoid cell lines from a healthy individual (control) andan I-cell disease patient DiCioccio and Miller, Glycobiology,1, 595604 (1991)]. Phosphoserine was found in immunoprecipitable-L-fucosidase of both control and I-cell lymphoid cells, butmannose 6-phosphate was identified only in enzyme of controlcells. Extension of this investigation to lymphoid culturesof a pseudo-Hurler polydystrophy patient also identified onlyphosphoserine in -L-fucosidase. Using 3H] mannose instead of32Pi, the precise identification of mannose 6-phosphate in -L-fucosidaseof control cells, and its absence in -L-fucosidase of I-celland pseudo-Hurler cells, was established. The stoichiometryof phosphorylation of -L-fucosidase in I-cell, pseudo-Hurlerand control lymphoid cells was 3, 4 and 10 mol Pi/mol enzyme,respectively. -L-Fucosidase was located in lysosomes isolatedfrom control, I-cell and pseudo-Hurler lymphoid cells by subcelluarfractionation on Percoll density gradients. Both I-cell andpseudo-Hurler lymphoid cells displayed normal intralysosomalactivity of -L-fucosidase despite lack of the mannose 6-phosphatemarker. Thus, I-cell and pseudo-Hurler lymphoid cells must possessa mannose 6-phosphate-independent mechanism for directing -L-fucosidaseto lysosomes. Phosphorylation of -L-fucosidase in pseudo-Hurlerand I-cell lymphoid cultures was found almost exclusively inintracellular and not in extracellular enzyme, suggesting thatphosphoserine may participate in the localization of -L-fucosidasein lysosomes of these cells. -L-fucosidase I-cell disease lysosome phosphorylation pseudo-Hurler polydystrophy |
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