PIK1, an essential phosphatidylinositol 4-kinase associated with the yeast nucleus.

Garcia-Bustos, Jose; Marini, Federica; Stevenson, I. L.; Frei, C.; Hall, Michael N.

doi:10.1002/j.1460-2075.1994.tb06519.x

Cited by 113 publications

(87 citation statements)

References 75 publications

(90 reference statements)

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“…Previous studies reported that this enzyme localizes to the TGN and the nucleus (Garcia-Bustos et al, 1994;Walch-Solimena and Novick, 1999;Sciorra et al, 2005;Strahl et al, 2005). A similar dual localization has been found for PI 4-kinase III␤ (Godi et al, 1999;de Graaf et al, 2002).…”

Section: Regulated Localization Of Pi-metabolizing Enzymes To Controlsupporting

confidence: 66%

“…In addition to their TGN localization, both Pik1p and PI 4-kinase III␤ also localize to the nucleus (Garcia-Bustos et al, 1994;Walch-Solimena and Novick, 1999;de Graaf et al, 2002;Strahl et al, 2005). Although the nuclear function of the two PI 4-kinases remains unknown, it has been demonstrated that they undergo nucleocytoplasmic shuttling (de Graaf et al, 2002;Strahl et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Nucleocytoplasmic Shuttling of the Golgi Phosphatidylinositol 4-Kinase Pik1 Is Regulated by 14-3-3 Proteins and Coordinates Golgi Function with Cell Growth

Demmel

Beck

Klose

et al. 2008

MBoC

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The yeast phosphatidylinositol 4-kinase Pik1p is essential for proliferation, and it controls Golgi homeostasis and transport of newly synthesized proteins from this compartment. At the Golgi, phosphatidylinositol 4-phosphate recruits multiple cytosolic effectors involved in formation of post-Golgi transport vesicles. A second pool of catalytically active Pik1p localizes to the nucleus. The physiological significance and regulation of this dual localization of the lipid kinase remains unknown. Here, we show that Pik1p binds to the redundant 14-3-3 proteins Bmh1p and Bmh2p. We provide evidence that nucleocytoplasmic shuttling of Pik1p involves phosphorylation and that 14-3-3 proteins bind Pik1p in the cytoplasm. Nutrient deprivation results in relocation of Pik1p from the Golgi to the nucleus and increases the amount of Pik1p–14-3-3 complex, a process reversed upon restored nutrient supply. These data suggest a role of Pik1p nucleocytoplasmic shuttling in coordination of biosynthetic transport from the Golgi with nutrient signaling.

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Section: Regulated Localization Of Pi-metabolizing Enzymes To Controlsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Nucleocytoplasmic Shuttling of the Golgi Phosphatidylinositol 4-Kinase Pik1 Is Regulated by 14-3-3 Proteins and Coordinates Golgi Function with Cell Growth

Demmel

Beck

Klose

et al. 2008

MBoC

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“…Regardless of the medium, both pik1 ts mutants failed to grow above 34°C, whereas the otherwise isogenic parental strain (YES32) grew well at all temperatures tested, but perhaps less robustly at the highest temperature examined (37°C) ( Table I). Addition of 1 M sorbitol to the medium improved the growth of the pik1 ts mutants only slightly, as observed for other pik1 ts alleles (27). These same strains were labeled with myo- [2-3 H]inositol, shifted from permissive (29°C) to restrictive (37°C) temperature for 1 h, and then lipids were extracted and analyzed by HPLC as above (Fig.…”

Section: Ptdins(4)p Level Is Reduced In Pik1mentioning

confidence: 68%

“…Pik1p is a cytosolic enzyme (25) that can be targeted to membranes via its interaction with a small Ca 2ϩ -binding protein (26). One report described Pik1p in the nucleus and suggested that loss of PIK1 function interferes with cytokinesis through effects on the actin cytoskeleton (27). The STT4 gene was uncovered in a screen for mutants defective in the pathway upstream of the protein kinase, Pkc1p (28).…”

Section: M(ip)mentioning

confidence: 99%

“…Mutants-It has been demonstrated previously that, like SEC14, PIK1 is an essential gene (23,27). If the pool of PtdIns(4)P in Golgi membranes is supplied by Pik1p and is important for secretion, then cells carrying temperature-conditional pik1 alleles should show a reduction in PtdIns(4)P at restrictive temperature and should manifest a corresponding defect in secretion.…”

Section: Ptdins(4)p Level Is Reduced In Pik1mentioning

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

265

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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Biochemistry, cell biology and molecular biology of lipids ofSaccharomyces cerevisiae

Daum

Lees

Bard

et al. 1998

Yeast

579

380

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The yeast Saccharomyces cerevisiae is a powerful experimental system to study biochemical, cell biological and molecular biological aspects of lipid synthesis. Most but not all genes encoding enzymes involved in fatty acid, phospholipid, sterol or sphingolipid biosynthesis of this unicellular eukaryote have been cloned, and many gene products have been functionally characterized. Less information is available about genes and gene products governing the transport of lipids between organelles and within membranes, turnover and degradation of complex lipids, regulation of lipid biosynthesis, and linkage of lipid metabolism to other cellular processes. Here we summarize current knowledge about lipid biosynthetic pathways in S. cerevisiae and describe the characteristic features of the gene products involved. We focus on recent discoveries in these fields and address questions on the regulation of lipid synthesis, subcellular localization of lipid biosynthetic steps, cross‐talk between organelles during lipid synthesis and subcellular distribution of lipids. Finally, we discuss distinct functions of certain key lipids and their possible roles in cellular processes. © 1998 John Wiley & Sons, Ltd.

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PIK1, an essential phosphatidylinositol 4-kinase associated with the yeast nucleus.

Cited by 113 publications

References 75 publications

Nucleocytoplasmic Shuttling of the Golgi Phosphatidylinositol 4-Kinase Pik1 Is Regulated by 14-3-3 Proteins and Coordinates Golgi Function with Cell Growth

Nucleocytoplasmic Shuttling of the Golgi Phosphatidylinositol 4-Kinase Pik1 Is Regulated by 14-3-3 Proteins and Coordinates Golgi Function with Cell Growth

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

Biochemistry, cell biology and molecular biology of lipids ofSaccharomyces cerevisiae

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