Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The endoplasmic reticulum of mammalian cells contains a heat shock protein of approximately 70 kDa (hsp70) termed binding protein BiP that is thought to promote the folding and subunit assembly of newly synthesized proteins. To study BiP function, we placed the BiP-encoding gene from Saccharomyces cerevisiae under the control of a regulated promoter and examined the effects of BiP depletion. Reduction of BiP protein to about 15% of normal levels led to a profound reduction in secretion of alpha factor and invertase. At the same time, unglycosylated precursors of these proteins accumulated intracellularly. The predominant form of the invertase precursor had undergone signal sequence cleavage but accumulated as a soluble species in the cytosol. In contrast, the alpha-factor precursor was exclusively in the signal-uncleaved form. It sedimented with microsomal membranes and was exposed at the cytoplasmic face in a protease-resistant form. These findings suggest that, in yeast, BiP function is required for translocation of soluble proteins into the endoplasmic reticulum at a stage beyond the initial nascent chain-membrane association.
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PMID:Binding protein BiP is required for translocation of secretory proteins into the endoplasmic reticulum in Saccharomyces cerevisiae. 199 57

When nuclear localization sequences (termed NLS) are placed at the N terminus of cytochrome c1, a mitochondrial inner membrane protein, the resulting hybrid proteins do not assemble into mitochondria when synthesized in the yeast Saccharomyces cerevisiae. Cells lacking mitochondrial cytochrome c1, but expressing the hybrid NLS-cytochrome c1 proteins, are unable to grow on glycerol since the hybrid proteins are associated primarily with the nucleus. A similar hybrid protein with a mutant NLS is transported to and assembled into the mitochondria. To identify proteins that might be involved in recognition of nuclear localization signals, we isolated conditional-lethal mutants (npl, for nuclear protein localization) that missorted NLS-cytochrome c1 to the mitochondria, allowing growth on glycerol. The gene corresponding to one complementation group (NPL1) encodes a protein with homology to DnaJ, an Escherichia coli heat shock protein. npl1-1 is allelic to sec63, a gene that affects transit of nascent secretory proteins across the endoplasmic reticulum. Rothblatt, J. A., R. J. Deshaies, S. L. Sanders, G. Daum, and R. Schekman. 1989. J. Cell Biol. 109:2641-2652. The npl1 mutants reported here also weakly affect translocation of preprocarboxypeptidaseY across the ER membrane. A normally nuclear hybrid protein containing a NLS fused to invertase and a nucleolar protein are not localized to the nucleus in npl1/sec63 cells at the nonpermissive temperature. Thus, NPL1/SEC63 may act at a very early common step in localization of proteins to the nucleus and the ER. Alternatively, by affecting ER and nuclear envelope assembly, npl1 may indirectly alter assembly of proteins into the nucleus.
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PMID:A yeast gene important for protein assembly into the endoplasmic reticulum and the nucleus has homology to DnaJ, an Escherichia coli heat shock protein. 255 4

We reported previously that Gts1p regulates oscillations of heat resistance in concert with those of energy metabolism in continuous cultures of the yeast Saccharomyces cerevisiae by inducing fluctuations in the levels of trehalose, but not in those of Hsp104 (heat shock protein 104). Further, the expression of TPS1, encoding trehalose-6-phosphate synthase 1, and HSP104 was activated by Gts1p in combination with Snf1 kinase, a transcriptional activator of glucose-repressible genes, in batch cultures under derepressed conditions. Here we show that, in continuous cultures, the mRNA level of TPS1 increased 6-fold in the early respiro-fermentative phase, while that of HSP104 did not change. The expression of SUC2, a representative glucose-repressible gene encoding invertase, also fluctuated, suggesting the involvement of the Snf1 kinase in the periodic activation of these genes. However, this possibility was proven to be unlikely, since the oscillations in both TPS1 and SUC2 mRNA expression were reduced by approx. 3-fold during the transient oscillation in gts1Delta (GTS1-deleted) cells, in which the energy state determined by extracellular glucose and intracellular adenine nucleotide levels was comparable with that in wild-type cells. Furthermore, neither the mRNA level nor the phosphorylation status of Snf1p changed significantly during the oscillation. Thus we suggest that Gts1p plays a major role in the oscillatory expression of TPS1 and SUC2 in continuous cultures of Saccharomyces cerevisiae, and hypothesized that Gts1p stabilizes oscillations in energy metabolism by activating trehalose synthesis to facilitate glycolysis at the shift from the respiratory to the respiro-fermentative phase.
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PMID:Gts1p stabilizes oscillations in energy metabolism by activating the transcription of TPS1 encoding trehalose-6-phosphate synthase 1 in the yeast Saccharomyces cerevisiae. 1522 82

Reduced cell wall invertase (CWIN) activity has been shown to be associated with poor seed and fruit set under abiotic stress. Here, we examined whether genetically increasing native CWIN activity would sustain fruit set under long-term moderate heat stress (LMHS), an important factor limiting crop production, by using transgenic tomato (Solanum lycopersicum) with its CWIN inhibitor gene silenced and focusing on ovaries and fruits at 2 d before and after pollination, respectively. We found that the increase of CWIN activity suppressed LMHS-induced programmed cell death in fruits. Surprisingly, measurement of the contents of H2O2 and malondialdehyde and the activities of a cohort of antioxidant enzymes revealed that the CWIN-mediated inhibition on programmed cell death is exerted in a reactive oxygen species-independent manner. Elevation of CWIN activity sustained Suc import into fruits and increased activities of hexokinase and fructokinase in the ovaries in response to LMHS Compared to the wild type, the CWIN-elevated transgenic plants exhibited higher transcript levels of heat shock protein genes Hsp90 and Hsp100 in ovaries and HspII17.6 in fruits under LMHS, which corresponded to a lower transcript level of a negative auxin responsive factor IAA9 but a higher expression of the auxin biosynthesis gene ToFZY6 in fruits at 2 d after pollination. Collectively, the data indicate that CWIN enhances fruit set under LMHS through suppression of programmed cell death in a reactive oxygen species-independent manner that could involve enhanced Suc import and catabolism, HSP expression, and auxin response and biosynthesis.
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PMID:Cell Wall Invertase Promotes Fruit Set under Heat Stress by Suppressing ROS-Independent Cell Death. 2746 84