VACUOLAR CARBOXYPEPTIDASE-Y OF SACCHAROMYCES-CEREVISIAE IS GLYCOSYLATED, SORTED AND MATURED IN THE FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

Vacuolar carboxypeptidase Y of Saccharomyces cerevisiae (CPYSC) has be en expressed in a Schizosaccharomyces pombe strain devoid of the endog enous equivalent peptidase, employing a 2 mu derived plasmid. Immunobl ot analysis revealed that CPYSC produced in the fission yeast has a hi gher molecular mass than mature CPYSC produced by the budding yeast. C PYSC is glycosylated when expressed in S. pombe and uses four N-linked glycosylation sites as shown by endoglycosidase H digestion. Carbohyd rate removal leads to a protein moiety which is indistinguishable in s ize from deglycosylated CPYSC produced by S. cerevisiae. CPYSC isolate d from S. pombe soluble extracts is enzymatically active and thus is p resumed to undergo correct proteolytic maturation. Subcellular fractio nation experiments showed a cofractionation of CPYSC with the S. pombe endoproteinases PrA and PrB, suggesting that the protein is correctly sorted to the vacuole and that these peptidases might be responsible for zymogen activation.