Biogenesis of gp80, the GPI-anchored cohesion protein in D. discoideum.
We have begun to assess the contributions made by co- and post-translational modifications to the physical properties of the D. discoideum protein gp80, and its sensitivity to hydrolysis by an endogenous GPI-PLC like activity. Two-dimensional gel electrophoresis indicates that the presence of various gp80 isoforms reflects the differential processing of its N-linked oligosaccharides. The presence or absence of this modification does not, however, appear to alter the sensitivity of the protein to the endogenous GPI-PIPLC activity. gp80 synthesized in cells defective in O-glycosylation is found predominantly in the medium as proteolytic products. The relationship of the O-linked modifications to the endogenous GPI-PIPLC activity is not yet clear. However, their absence does not alter the sensitivity of gp80 to exogenous GPI-PIPLC. We attempted to inhibit the GPI anchoring of gp80 using mannoseamine. Although cells displayed a reversible block in the onset of aggregation and gp80 synthesis, this did not appear to reflect changes in anchoring. The contribution is now being examined in chimeric proteins.
Klein
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E.A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, MO 63104.
Pauly
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DaSilva
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D000818:Animals; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D004023:Dictyostelium / Q000737:chemistry*; D015180:Electrophoresis, Gel, Two-Dimensional; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014415:Tunicamycin
D015815:Cell Adhesion Molecules; D005656:Fungal Proteins; D017261:Glycosylphosphatidylinositols; D015800:Protozoan Proteins; D014415:Tunicamycin; D010727:Phosphoric Diester Hydrolases