SEC14-dependent Secretion inSaccharomyces cerevisiae

Stock, Stephen D.; Hama, Hiroko; DeWald, Daryll B.; Takemoto, Jon Y.

doi:10.1074/jbc.274.19.12979

Cited by 48 publications

(27 citation statements)

References 30 publications

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“…6). DISCUSSION We recently demonstrated that a mutation, sac1-22, that suppresses the growth and secretion defect of sec14-3 mutants causes a specific and pronounced elevation in the cellular level of PtdIns(4)P (19). It was also demonstrated by others that SAC1 encodes a novel multifunctional phosphoinositide phosphatase that can use PtdIns(4)P, among other phosphoinositides, as a substrate (20).…”

Section: Delivery Of Cpy To the Vacuole Is Not Blocked In Pik1 Tsmentioning

confidence: 82%

“…When cultures reached midexponential phase (A 600 nm ϭ ϳ0.8), one-half of each culture was shifted to 37°C for 1 h prior to termination of growth by addition of trichloroacetic acid (5% final concentration). Extraction of lipids and their analysis by high pressure liquid chromatography (HPLC) were carried out as described in detail previously (19,37).…”

Section: Methodsmentioning

confidence: 99%

“…2 C is the terminal sphingolipid in S. cerevisiae (17), and its biosynthesis by Ipt1p is coupled to PtdIns consumption and DAG production (18). One of our laboratories recently re-examined the properties of the sec14-3 sac1-22 double mutant and found that the species attributed to M(IP) 2 C had been misidentified and that suppression did not require either Ipt1p function or an elevated DAG level (19). Moreover, analysis of phospholipid composition showed that the sec14-3 sac1-22 cells contained 8-fold more PtdIns(4)P than either sec14-3 SAC1 or SEC14 SAC1 strains (19).…”

mentioning

confidence: 99%

“…One of our laboratories recently re-examined the properties of the sec14-3 sac1-22 double mutant and found that the species attributed to M(IP) 2 C had been misidentified and that suppression did not require either Ipt1p function or an elevated DAG level (19). Moreover, analysis of phospholipid composition showed that the sec14-3 sac1-22 cells contained 8-fold more PtdIns(4)P than either sec14-3 SAC1 or SEC14 SAC1 strains (19). The fact that a sac1 loss-of-function mutation caused an elevation in PtdIns(4)P was readily explained by the contemporaneous demonstration that Sac1p is a phosphoinositide phosphatase (20).…”

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confidence: 99%

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Direct Involvement of Phosphatidylinositol 4-Phosphate in Secretion in the Yeast Saccharomyces cerevisiae

Hama¹,

Schnieders²,

Thorner³

et al. 1999

Journal of Biological Chemistry

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266

268

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The SEC14 gene encodes an essential phosphatidylinositol (PtdIns) transfer protein required for formation of Golgi-derived secretory vesicles in yeast. Suppressor mutations that rescue temperature-sensitive sec14 mutants provide an approach for determining the role of Sec14p in secretion. One suppressor, sac1-22, causes accumulation of PtdIns(4)P. SAC1 encodes a phosphatase that can hydrolyze PtdIns(4)P and certain other phosphoinositides. These findings suggest that PtdIns(4)P is limiting in sec14 cells and that elevation of PtdIns(4)P production can suppress the secretory defect. Correspondingly, we found that PtdIns(4)P levels were decreased significantly in sec14-3 mutants shifted to 37°C and that sec14-3 cells could grow at an otherwise nonpermissive temperature (34°C) when carrying a plasmid overexpressing PIK1, encoding one of two essential PtdIns 4-kinases. This effect is specific because overexpression of the other PtdIns 4-kinase gene (STT4) or a PtdIns 3-kinase gene (VPS34) did not rescue sec14-3 cells. To further address Pik1p function in secretion, two different pik1 ts mutants were examined. Upon shift to restrictive temperature (37°C), the PtdIns(4)P levels dropped by about 60% in both pik1 ts strains within 1 h. During the same period, cells displayed a reduction (40 -50%) in release of a secreted enzyme (invertase). However, similar treatment did not effect maturation of a vacuolar enzyme (carboxypeptidase Y). These findings indicate that, first, PtdIns(4)P limitation is a major contributing factor to the secretory defect in sec14 cells; second, Sec14p function is coupled to the action of Pik1p, and; third, PtdIns(4)P has an important role in the Golgi-toplasma membrane stage of secretion.In eukaryotic cells, secreted proteins are synthesized on ribosomes targeted to the endoplasmic reticulum (ER), 1 translocated into the ER lumen, and transported through the secretory pathway (1). From the ER, secretory proteins are transported to the Golgi apparatus, through the subcompartments of the Golgi, and then to the cell surface or to certain intracellular organelles, all via small membrane-bound vesicles (transport vesicles) (2-4). Cargo proteins are packaged into transport vesicles that bud from one compartment and fuse with another. Mechanisms of vesicle budding and fusion are conserved from yeast to mammalian cells (3,5). Because of its tractability for genetic analysis, bakers' yeast (Saccharomyces cerevisiae) has proven to be a useful organism to identify gene products required for various events in secretion. Genetic screens, first applied by Schekman and co-workers (6), resulted in the isolation of temperature-sensitive sec mutants that displayed defects in different stages of secretion at the nonpermissive temperature. Characterization of the corresponding normal (SEC) genes has pinpointed many proteins necessary for secretory processes; and, a large number of gene products are now known to function at various steps in the secretory pathway (reviewed in Ref. 7). The SEC14 gene encodes a phosph...

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Section: Delivery Of Cpy To the Vacuole Is Not Blocked In Pik1 Tsmentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Direct Involvement of Phosphatidylinositol 4-Phosphate in Secretion in the Yeast Saccharomyces cerevisiae

Hama¹,

Schnieders²,

Thorner³

et al. 1999

Journal of Biological Chemistry

Self Cite

266

268

View full text Add to dashboard Cite

show abstract

“…Analysis of bypass mutants has led to the suggestion that Sec14p is required for maintenance of a critical pool of diacylglycerol [21,22]. Moreover, Sec14p can also fa-cilitate PtdIns4P production in i o [22,23] ; this lipid might also be a critical requirement in protein secretion. In another yeast, Yarrowia lipolytica, SEC14 is not an essential gene and is required only for differentiation from yeast to a mycelial growth form [24].…”

Section: Introductionmentioning

confidence: 99%

Purification and cloning of phosphatidylinositol transfer proteins from Dictyostelium discoideum: homologues of both mammalian PITPs and Saccharomyces cerevisiae Sec14p are found in the same cell

Swigart

Insall

Cockcroft

2000

Biochemical Journal

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Soluble phosphatidylinositol transfer proteins (PITPs) have important roles in lipid-mediated signalling as well as in membrane traffic. Two PITPs (α and β) have been cloned from mammalian cells, which are unrelated in sequence to yeast PITP (the product of the SEC14 gene). However, all three PITPs can perform interchangeably to reconstitute function in mammalian cells. We have now purified the major PITP from the cytoplasm of Dictyostelium discoideum and cloned the gene. This protein, DdPITP1, is homologous with mammalian PITPα and PITPβ. We have also cloned a second gene (DdPITP2) related in sequence to DdPITP1. In addition, an independently cloned cDNA encodes a relative of the SEC14 family of yeast PITPs. DdPITP1, DdPITP2 and DdSec14 proteins were all able to mediate the transfer of PtdIns from one membrane compartment to another; they thus exhibited the hallmark of PITPs. Secondly, all three PITPs were able to rescue phospholipase C-mediated phosphoinositide hydrolysis in PITP-depleted HL60 cells, indicating that all three PITPs were capable of stimulating phosphoinositide synthesis. The identification of PITPs related to both mammalian PITPs and yeast Sec14p in a single organism will provide a unique opportunity to examine the functions of this class of protein with genetic approaches.

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Sphingolipid‐enriched domains in fungi

et al. 2020

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Plasma membrane carries out multiple physiological functions that require its dynamic and tightly regulated organization into specialized domains of different size, stability, and lipid/protein composition. Sphingolipids are a group of lipids in which the plasma membrane is particularly enriched, thus being crucial for its structure and function. A specific type of sphingolipid‐enriched plasma membrane domains, where ergosterol is depleted and lipids are tightly packed in a rigid gel phase, has recently been found in several fungal species, including yeasts and moulds. After presenting the main biophysical features of gel domains and the experimental method for their detection in the fungal plasma membrane, we review these sphingolipid‐enriched gel domains and illustrate their importance to both unicellular and multicellular fungi. First, the biophysical properties of the fungal sphingolipid‐enriched domains will be analysed taking into consideration the plasma membrane sphingolipidome. Next, their possible biological roles will be summarized, including their relations with plasma membrane compartments and involvement in stress responses. Moreover, since the plasma membrane is a target for several antifungal compounds, a biophysical connection between sphingolipid‐enriched domains and antifungal action will be explored.

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SEC14-dependent Secretion inSaccharomyces cerevisiae

Cited by 48 publications

References 30 publications

Direct Involvement of Phosphatidylinositol 4-Phosphate in Secretion in the Yeast Saccharomyces cerevisiae

Direct Involvement of Phosphatidylinositol 4-Phosphate in Secretion in the Yeast Saccharomyces cerevisiae

Purification and cloning of phosphatidylinositol transfer proteins from Dictyostelium discoideum: homologues of both mammalian PITPs and Saccharomyces cerevisiae Sec14p are found in the same cell

Sphingolipid‐enriched domains in fungi

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