A deletion that includes the segment coding for the signal peptidase cleavage site delays release of Saccharomyces cerevisiae acid phosphatase from the endoplasmic reticulum.
We studied ultrastructural localization of acid phosphatase in derepressed Saccharomyces cerevisiae cells transformed with a multicopy plasmid carrying either the wild-type PHO5 gene or a PHO5 gene deleted in the region overlapping the signal peptidase cleavage site. Wild-type enzyme was located in the cell wall, as was 50% of the modified protein, which carried high-mannose-sugar chains. The remaining 50% of the protein was active and core glycosylated, and it accumulated in the endoplasmic reticulum cisternae. The signal peptide remained uncleaved in both forms. Cells expressing the modified protein exhibited an exaggerated endoplasmic reticulum with dilated lumen.
D000135:Acid Phosphatase / Q000235:genetics*; D002872:Chromosome Deletion; D010450:Endopeptidases / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure; D005796:Genes; D005800:Genes, Fungal; D008565:Membrane Proteins; D008854:Microscopy, Electron; D009154:Mutation; D021382:Protein Sorting Signals / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000648:ultrastructure; D012697:Serine Endopeptidases
D008565:Membrane Proteins; D021382:Protein Sorting Signals; D000135:Acid Phosphatase; D010450:Endopeptidases; D012697:Serine Endopeptidases; C026515:type I signal peptidase