Glycosylation and secretion of acid phosphatase in Schizosaccharomyces pombe.
We have purified secreted acid phosphatase of Schizosaccharomyces pombe. The enzyme is N-glycosylated, the associated carbohydrate accounts for 90% of the total molecular mass and the protein moiety has a molecular mass of 54 kDa. The deglycosylated enzyme still exhibits enzymatic activity. Using antibodies recognizing the protein moiety of the enzyme we have identified two intracellular precursors of acid phosphatase: an unglycosylated membrane-bound 54-kDa form that accumulates in the presence of tunicamycin and a partially glycosylated 72-kDa form that accumulates mostly in membranes of cells grown in rich medium. We further showed that the conversion of the 54-kDa and 72-kDa forms to partially glycosylated and fully glycosylated acid phosphatase is a regulated process. Growth conditions determine how much of translated 54-kDa acid phosphatase is glycosylated to the 72-kDa form and how much remains unglycosylated in membranes. When cells are grown in a rich medium, 5% of the total acid phosphatase protein remains as unglycosylated enzyme and 8% as partially glycosylated 72-kDa form. In cells grown in the minimal medium, however, all of the 54-kDa and 72-kDa forms of acid phosphatase are rapidly processed to fully glycosylated enzyme. The 72-kDa form and the unglycosylated form of acid phosphatase are not secreted or transported to the plasma membrane.
D000135:Acid Phosphatase / Q000032:analysis / Q000378:metabolism*; D001345:Autoradiography; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000032:analysis; D002462:Cell Membrane / Q000201:enzymology; D003470:Culture Media; D004718:Saccharomycetales / Q000201:enzymology*; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000254:growth & development
D002241:Carbohydrates; D003470:Culture Media; D000135:Acid Phosphatase