Protein Sorting in Saccharomyces cerevisiae : Isolation of Mutants Defective in the Delivery and Processing of Multiple Vacuolar Hydrolases

作者：Jane S. Robinson, Daniel J. Klionsky, Lois M. Banta, Scott D. Emr · 发表于：Molecular and Cellular Biology · 年份：1988 · DOI：10.1128/mcb.8.11.4936-4948.1988 · 被引用次数：351 · 研究领域：Cellular transport and secretion、Lysosomal Storage Disorders Research、Studies on Chitinases and Chitosanases

Using a selection for spontaneous mutants that mislocalize a vacuolar carboxypeptidase Y (CPY)-invertase fusion protein to the cell surface, we identified vacuolar protein targeting (vpt) mutants in 25 new vpt complementation groups. Additional alleles in each of the eight previously identified vpt complementation groups (vpt1 through vpt8) were also obtained. Representative alleles from each of the 33 vpt complementation groups (vpt1 through vpt33) were shown to exhibit defects in the sorting and processing of several native vacuolar proteins, including the soluble hydrolases CPY, proteinase A, and proteinase B. Of the 33 complementation groups, 19 were found to contain mutant alleles that led to extreme defects. In these mutants, CPY accumulated in its Golgi complex-modified precursor form which was secreted by the mutant cells. Normal protein secretion appeared to be unaffected in the vpt mutants. The lack of significant leakage of cytosolic markers from the vpt mutant cells indicated that the vacuolar protein-sorting defects associated with these mutants do not result from cell lysis. In addition, the observation that the precursor rather than the mature forms of CPY, proteinase A, proteinase B were secreted from the vpt mutants was consistent with the fact that mislocalization occurred at a stage after Golgi complex-specific modification, but before final vacuolar sorting of these enzymes. Vacuolar membrane protein sorting appeared to be unaffected in the majority of the...