Defective plasma membrane assembly in yeast secretory mutants

Tschopp, Juerg; Esmon, P C; Schekman, Randy

doi:10.1128/jb.160.3.966-970.1984

Cited by 42 publications

(21 citation statements)

References 18 publications

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“…These high mol. wt proteins appeared with kinetics reflecting the slow recovery of secl8 cells from the heat induced secretion block (Tschopp et al, 1984). This experiment, however, is not a true pulse-chase experiment.…”

Section: Resultsmentioning

confidence: 79%

Myoinositol gets incorporated into numerous membrane glycoproteins of Saccharomyces cerevisiae; incorporation is dependent on phosphomannomutase (sec53).

1990

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We recently described a 125 kd membrane glycoprotein in Saccharomyces cerevisiae which is anchored in the lipid bilayer by an inositol‐containing phospholipid. We now find that when S. cerevisiae cells are metabolically labeled with [3H]myoinositol, many glycoproteins become labeled more strongly than the 125 kd protein. Myoinositol is attached to these glycoproteins as part of a phospholipid moiety which resembles glycophospholipid anchors of other organisms. Labeling of proteins with [3H]myoinositol for short times and in secretion mutants blocked at various stages of the secretory pathway shows that these phospholipid moieties can be added to proteins in the endoplasmic reticulum and that these proteins are transported to the Golgi by the regular secretory pathway. sec53, a mutant which cannot produce GDP‐mannose at 37 degrees C, does not incorporate myoinositol or palmitic acid into membrane glycoproteins at this temperature, suggesting that GDP‐mannose is required for the biosynthesis of these phospholipid moieties. All other secretion and glycosylation mutants tested add phospholipid moieties to proteins normally.

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Section: Resultsmentioning

confidence: 79%

Myoinositol gets incorporated into numerous membrane glycoproteins of Saccharomyces cerevisiae; incorporation is dependent on phosphomannomutase (sec53).

1990

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“…An explanation for two populations of post-Golgi vesicles is that one population, transporting materials for plasma membrane and cell-wall synthesis, such as the major plasma membrane ATPase, Pmalp, and the cell-wall component, Bgl2p, is specifically targeted to regions of active growth, while another population, carrying periplas-mic enzymes and proteins secreted into the medium (invertase, acid phosphatase, Exglp), does not need to be targeted so precisely. This model predicts that other secreted proteins shown to accumulate in sec mutants but not directly involved in surface expansion, such as the periplasmic enzyme o~-galactosidase (Tschopp et al, 1984) and several plasma membrane permeases (sulfate, galactose, and arginine permease [Novick et al, 1980;Tschopp et al, 1984]) should be present in the invertase-containing vesicles but not in vesicles transporting Bgl2p.…”

Section: Discussionmentioning

confidence: 99%

Parallel secretory pathways to the cell surface in yeast.

Harsay

Bretscher

1995

The Journal of Cell Biology

236

263

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Saccharomyces cerevisiae mutants that have a post-Golgi block in the exocytic pathway accumulate 100-nm vesicles carrying secretory enzymes as well as plasma membrane and cell-wall components. We have separated the vesicle markers into two groups by equilibrium isodensity centrifugation. The major population of vesicles contains Bg12p, an endoglucanase destined to be a cell-wall component, as well as Pma1p, the major plasma membrane ATPase. In addition, Snc1p, a synaptobrevin homologue, copurifies with these vesicles. Another vesicle population contains the periplasmic enzymes invertase and acid phosphatase. Both vesicle populations also contain exoglucanase activity; the major exoglucanase normally secreted from the cell, encoded by EXG1, is carried in the population containing periplasmic enzymes. Electron microscopy shows that both vesicle groups have an average diameter of 100 nm. The late secretory mutants sec1, sec4, and sec6 accumulate both vesicle populations, while neither is detected in wild-type cells, early sec mutants, or a sec13 sec6 double mutant. Moreover, a block in endocytosis does not prevent the accumulation of either vesicle species in an end4 sec6 double mutant, further indicating that both populations are of exocytic origin. The accumulation of two populations of late secretory vesicles indicates the existence of two parallel routes from the Golgi to the plasma membrane.

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“…In addition, the transport of Ath1p to vacuoles via the secretory pathway as proposed from previous works [101,104] is doubtful since the amino acid sequence of this protein does not present any signal sequence and consensus cleavage sites characteristic of proteins following this pathway [8]. It is therefore suggested that the acid trehalase can be secreted to the periplasm similarly to the externalization of some permeases and H -ATPase [114,115]. The acid trehalase and extracellular trehalose will then be internalized from the surface and delivered to the vacuoles by endocytosis.…”

Section: Hydrolysis By Neutral (Nth1p Nth2p) and Acid (Ath1p) Trehalmentioning

confidence: 96%

Reserve carbohydrates metabolism in the yeast Saccharomyces cerevisiae

François¹

2001

FEMS Microbiology Reviews

323

368

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Glycogen and trehalose are the two glucose stores of yeast cells. The large variations in the cell content of these two compounds in response to different environmental changes indicate that their metabolism is controlled by complex regulatory systems. In this review we present information on the regulation of the activity of the enzymes implicated in the pathways of synthesis and degradation of glycogen and trehalose as well as on the transcriptional control of the genes encoding them. cAMP and the protein kinases Snf1 and Pho85 appear as major actors in this regulation. From a metabolic point of view, glucose-6-phosphate seems the major effector in the net synthesis of glycogen and trehalose. We discuss also the implication of the recently elucidated TOR-dependent nutrient signalling pathway in the control of the yeast glucose stores and its integration in growth and cell division. The unexpected roles of glycogen and trehalose found in the control of glycolytic flux, stress responses and energy stores for the budding process, demonstrate that their presence confers survival and reproductive advantages to the cell. The findings discussed provide for the first time a teleonomic value for the presence of two different glucose stores in the yeast cell.

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Defective plasma membrane assembly in yeast secretory mutants

Cited by 42 publications

References 18 publications

Myoinositol gets incorporated into numerous membrane glycoproteins of Saccharomyces cerevisiae; incorporation is dependent on phosphomannomutase (sec53).

Myoinositol gets incorporated into numerous membrane glycoproteins of Saccharomyces cerevisiae; incorporation is dependent on phosphomannomutase (sec53).

Parallel secretory pathways to the cell surface in yeast.

Reserve carbohydrates metabolism in the yeast Saccharomyces cerevisiae

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