title: Characterization of different forms of yeast acid trehalase in the secretory pathway.
abstract: The biosynthesis and processing of the vacuolar (lysosomal) acid trehalase (molecular mass about 220 kDa) was followed in vivo using mutants conditionally defective in the secretory pathway. A precursor of 41 kDa was found in sec61 mutant cells deficient in translocation of secretory protein precursors into the lumen of the endoplasmic reticulum. Endoglycosidase H and N-glycosidase F treatment of purified acid trehalase in vitro resulted in a 41 kDa band, indicating that the precursor form found in sec61 mutant cells corresponds to the carbohydrate-free form of the enzyme. sec18 mutant cells, blocked in the delivery of secretory proteins from the endoplasmic reticulum to the Golgi body accumulate a form with a molecular mass of 76 kDa which probably corresponds to a partially glycosylated precursor of the mature acid trehalase. This precursor partially disappears in favour of the appearance of a higher molecular weight component of 180 kDa in sec7 mutants which are blocked in the delivery step of secretory proteins from the Golgi body to the vacuole. In wild-type cells the fully glycosylated mature form of acid trehalase of about 220 kDa was observed accompanied by some 180 kDa and 76 kDa material.
authors.affiliation: Biochemisches Institut, Universität Freiburg, Federal Republic of Germany.
authors.forename: K
authors.initials: K
authors.lastname: Mittenbühler
authors.forename: H
authors.initials: H
authors.lastname: Holzer
mesh_terms: D001345:Autoradiography; D015153:Blotting, Western; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000648:ultrastructure; D014198:Trehalase / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D014617:Vacuoles / Q000201:enzymology
chemical_list: D014198:Trehalase