title: Processing and maturation of carboxypeptidase Y and alkaline phosphatase in Schizosaccharomyces pombe.
abstract: Schizosaccharomyces pombe carboxypeptidase Y (CPY) is synthesized as a zymogen and transported into the vacuole where maturation and activation occurs. The 110-kDa S. pombe CPY precursor is processed twice and finally converted to a mature form consisting of polypeptides of approximately 19 and 32 kDa linked by a single disulfide bond. In Saccharomyces cerevisiae, maturation of CPY occurs mostly through the activity of vacuolar aspartyl protease Pep4p, whereas a Pep4p homolog has not been found in the S. pombe genome database. Based on analysis of protease-deficient mutants, we found that S. pombe CPY was not able to be processed or activated in isp6Δpsp3Δ double disruptants. Both Isp6p and Psp3p are subtilase-type serine proteases with related sequences. Moreover, alkaline phosphatase of S. pombe was found to be localized at the vacuolar membrane and was also unprocessed in isp6Δpsp3Δ double disruptants. Vacuolar localization of GFP-fused Isp6p and Psp3p was determined by fluorescence microscopy. These results suggest that the two serine proteases Isp6p and Psp3p are functional in the vacuole and are involved in proteolytic processing of vacuolar proteins.
authors.affiliation: ASPEX Division, Research Center, Asahi Glass Co., Ltd., 1150 Hazawa-cho, Kanagawa, 221-8755, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Mukaiyama
authors.forename: Tomoko
authors.initials: T
authors.lastname: Iwaki
authors.forename: Alimjan
authors.initials: A
authors.lastname: Idiris
authors.forename: Kaoru
authors.initials: K
authors.lastname: Takegawa
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D043402:Cathepsin A / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism; D014617:Vacuoles / Q000201:enzymology / Q000235:genetics / Q000378:metabolism
chemical_list: D004792:Enzyme Precursors; D029702:Schizosaccharomyces pombe Proteins; D000469:Alkaline Phosphatase; D057057:Serine Proteases; D043402:Cathepsin A