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)

In eukaryotic cells, monomeric GTPases of the Ypt/Rab family function as regulators at defined steps of vesicular transport in exo- and endocytosis. Here we report on the isolation and characterization of two genes (YPT31 and YPT32) of the yeast Saccharomyces cerevisiae which encode members of the Ypt family exhibiting >80% sequence identity. Whereas the disruption of one of the two genes was phenotypically neutral, the disruption of both YPT31 and YPT32 led to lethality. Depletion of wild-type Ypt31p or of a short-lived ubiquitin-Ypt31p in a ypt32 null background led to a massive accumulation of Golgi-like membranes, an inhibition of invertase secretion and defects in vacuolar protein maturation. Similar alterations were observed in a conditional-lethal ypt31-1 mutant at 30 min after shift to the non-permissive temperature. According to subcellular fractionation, a significant part of Ypt31p appeared to be located in Golgi-enriched membrane fractions. In accordance with this, indirect immunofluorescence using affinity-purified anti-Ypt31p antibodies gave a punctate staining similar to that observed with Golgi-located proteins. From the phenotypic alterations observed in ypt31 and ypt32 mutants, it seems likely that the two GTPases are involved in intra-Golgi transport or in the formation of transport vesicles at the most distal Golgi compartment.
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PMID:Two GTPase isoforms, Ypt31p and Ypt32p, are essential for Golgi function in yeast. 897 73

The Saccharomyces cerevisiae actin-related protein Arp2p is an essential component of the actin cytoskeleton. We have tested its potential role in the endocytic and exocytic pathways by using a temperature-sensitive allele, arp2-1. The fate of the plasma membrane transporter uracil permease was followed to determine whether Arp2p plays a role in the endocytic pathway. Inhibition of normal endocytosis as revealed by maintenance of active uracil permease at the plasma membrane and strong protection against subsequent vacuolar degradation of the protein were observed in the mutant at the restrictive temperature. Furthermore, arp2-1 cells accumulated ubiquitin-permease conjugates, formed prior to internalization. These effects were also visible at permissive temperature, whereas the actin cytoskeleton appeared to be normally polarized. The soluble hydrolase carboxypeptidase Y and the lipophilic dye FM 4-64 were targeted normally to the vacuole in arp2-1 cells. Thus, Arp2p is required for internalization but does not play a major role in later steps of endocytosis. Synthetic lethality was demonstrated between arp2-1 and the endocytic mutant end3-1, suggesting participation of Arp2p and End3p in the same process. Finally, no evidence for a major defect in secretion was apparent; invertase secretion and delivery of uracil permease to the plasma membrane were unaffected in arp2-1 cells.
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PMID:The yeast actin-related protein Arp2p is required for the internalization step of endocytosis. 924 13

The split-ubiquitin technique was used to detect transient protein interactions in living cells. Nub, the N-terminal half of ubiquitin (Ub), was fused to Sec62p, a component of the protein translocation machinery in the endoplasmic reticulum of Saccharomyces cerevisiae. Cub, the C-terminal half of Ub, was fused to the C terminus of a signal sequence. The reconstitution of a quasi-native Ub structure from the two halves of Ub, and the resulting cleavage by Ub-specific proteases at the C terminus of Cub, serve as a gauge of proximity between the two test proteins linked to Nub and Cub. Using this assay, we show that Sec62p is spatially close to the signal sequence of the prepro-alpha-factor in vivo. This proximity is confined to the nascent polypeptide chain immediately following the signal sequence. In addition, the extent of proximity depends on the nature of the signal sequence. Cub fusions that bore the signal sequence of invertase resulted in a much lower Ub reconstitution with Nub-Sec62p than otherwise identical test proteins bearing the signal sequence of prepro-alpha-factor. An inactive derivative of Sec62p failed to interact with signal sequences in this assay. These in vivo findings are consistent with Sec62p being part of a signal sequence-binding complex.
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PMID:Detection of transient in vivo interactions between substrate and transporter during protein translocation into the endoplasmic reticulum. 995 Jun 80

Secretion of bovine pancreatic trypsin inhibitor (BPTI) in Saccharomyces cerevisiae was examined with four different leader peptides: the invertase signal peptide, the mfalpha1 signal peptide, a synthetic signal peptide, and a synthetic pre pro leader. BPTI secretion from a low-copy CEN plasmid varies from 1.8 to 10.4 microgram/mL among these constructs. Secretion titers correlate with dependence on signal recognition particle (SRP), with greatest secretion from the most SRP-dependent construct. Examination of co- vs post-translational translocation pathways and overall translocation efficiency by ubiquitin translocation assay (UTA) does not provide insight into the variation in BPTI secretion efficiency, perhaps due to alteration in translocation kinetics from the additional polypeptide fusion required by the assay. BPTI translocation efficiency (as measured by UTA) is found to drop markedly upon depletion of Srp54p, prior to any observable growth defect. Subsequent to stress response induction and the onset of slow growth (15-h doubling time), BPTI translocation efficiency recovers to the level observed prior to SRP depletion.
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PMID:Leader peptide efficiency correlates with signal recognition particle dependence in Saccharomyces cerevisiae. 1009 39

Varied intensities of nitrotyrosine immunoreactivity were detected by Western blots after the reaction of proteins or enzymes with peroxynitrite (PN), a strong oxidant derived from nitric oxide. Intense immunoreactivity of cAMP-dependent protein kinase, calmodulin and most histones may depend on greater access to tyrosine residues in the reaction, whereas the absence of immunoreactivity of caspase-3, ubiquitin and S-100 proteins may reflect lack of accessibility. In addition, the changes in UV/visible absorbency were observed after PN-treatment of polynucleotides, polypeptides or proteins. Brief PN-treatment of invertase increased its enzymatic activity. Furthermore, PN-treatment of rabbit IgG decreased its recognition by anti-IgG. The results suggest that PN may chemically modify polypeptides, proteins and polynucleotides and may subsequently alter their biological activity.
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PMID:Modification of proteins and polynucleotides by peroxynitrite. 1053 71

Candida albicans ubiquitin genes UBI3 and UBI4 encode a ubiquitin-hybrid protein involved in ribosome biogenesis and polyubiquitin, respectively. In this work we show that UBI3 and UBI4 promoter regions confer differential expression consistent with the function of their encoded gene products. Hybrid genes were constructed containing the SUC2 coding region under the control of UBI3 or UBI4 promoters in the yeast vector pLC7. Invertase production in Saccharomyces cerevisiae transformants was differentially regulated: the UBI4 promoter was induced by stress conditions (thermal upshift and/or starvation) whereas the UBI3 promoter conferred constitutive invertase production in growing yeast cells. These results indicate that the UBI4 promoter is regulated by stress-response signaling pathways, whereas the UBI3 promoter is controlled according to the requirement for protein synthesis to support cell growth.
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PMID:Candida albicans UBI3 and UBI4 promoter regions confer differential regulation of invertase production to saccharomyces cerevisiae cells in response to stress. 1210 35

Ssh1p of Saccharomyces cerevisiae is related in sequence to Sec61p, a general receptor for signal sequences and the major subunit of the channel that guides proteins across the membrane of the endoplasmic reticulum. The split-ubiquitin technique was used to determine whether Ssh1p serves as an additional receptor for signal sequences in vivo. We measured the interactions between the N(ub)-labeled Ssh1p and C(ub)-translocation substrates bearing four different signal sequences. The so-determined interaction profile of Ssh1p was compared with the signal sequence interaction profile of the correspondingly modified N(ub)-Sec61p. The assay reveals interactions of Ssh1p with the signal sequences of Kar2p and invertase, whereas Sec61p additionally interacts with the signal sequences of Mfalpha1 and carboxypeptidase Y. The measured physical proximity between Ssh1p and the beta-subunit of the signal sequence recognition particle receptor confirms our hypothesis that Ssh1p is directly involved in the cotranslational translocation of proteins across the membrane of the endoplasmic reticulum.
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PMID:Recognition of a subset of signal sequences by Ssh1p, a Sec61p-related protein in the membrane of endoplasmic reticulum of yeast Saccharomyces cerevisiae. 1213 63

The cell wall-associated glyceraldehyde-3-phosphate dehydrogenase (cwGAPDH) activity in Saccharomyces cerevisiae increases (two- to 10-fold, depending on the strain) in response to starvation and temperature upshift. Assays using transformants carrying pTDH, a yeast centromer derivative plasmid containing the Candida albicans TDH3 gene (encoding GAPDH) fused in frame with the yeast SUC2-coding region for internal invertase, showed that starvation and/or temperature upshift result in a similar increase in both cwGAPDH and cell wall-associated invertase activities. In addition, this incorporation of GAPDH protein into the cell wall in response to stress does not require (i) de novo protein synthesis, indicating that preexisting cytosolic enzyme is incorporated into the cell wall, (ii) nor the participation of the ubiquitin yeast stress response system, as no differences were observed between wild-type and polyubiquitin-depleted (Deltaubi4) strains.
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PMID:Starvation and temperature upshift cause an increase in the enzymatically active cell wall-associated glyceraldehyde-3-phosphate dehydrogenase protein in yeast. 1465 34

Internal breakdown in mango fruits has become a major concern in recent years. This disorder renders the fruits unfit for human consumption. The overall loss due to this disorder is about 35-55%. Environmental and physiological factors like high temperature, humidity, respiration and low transpiration rates have been attributed to cause spongy tissue due to reduced loss of heat from fruits. Biochemical studies have shown that there is a reduction in pH, total soluble solids, ascorbic acid, total sugars and carotenoids, low reducing and non-reducing sugar contents, lower amylase and invertase activities and high acid and starch content in spongy tissue affected pulp. There are no reports on molecular studies to determine changes in gene expression in these tissues. The present study was conducted using PCR based subtractive hybridization and RNA gel blot analysis of a few selected genes. The latter showed a higher expression of catalase, ubiquitin, alcohol dehydrogenase, coproporphyrinogen oxidase and keratin associated protein. A lower expression of ribosomal gene, fructose bisphosphate aldolase and cysthathionine gamma synthase was also noticed in spongy tissue. Biochemical studies indicated a lower amylase activity and a lower content of the total and reducing sugars in spongy tissue as compared to healthy tissue. Analyses of results indicate that oxidative stress may be one of the causes for formation of spongy tissue, which affects the expression of many genes. The role of these genes in spongy tissue formation is discussed.
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PMID:Cloning and characterization of differentially expressed genes of internal breakdown in mango fruit (Mangifera indica). 1630 21

MicroRNAs (miRNAs) are master regulators of gene activity documented to play central roles in fruit ripening in model plant species, yet little is known of their roles in Lycium barbarum L. fruits. In this study, miRNA levels in L. barbarum fruit samples at four developmental stages, were assayed using Illumina HiSeqTM2000. This revealed the presence of 50 novel miRNAs and 38 known miRNAs in L. barbarum fruits. Of the novel miRNAs, 36 were specific to L. barbarum fruits compared with L. chinense. A number of stage-specific miRNAs were identified and GO terms were assigned to 194 unigenes targeted by miRNAs. The majority of GO terms of unigenes targeted by differentially expressed miRNAs are "intracellular organelle," "binding," "metabolic process," "pigmentation," and "biological regulation." Enriched KEGG analysis indicated that nucleotide excision repair and ubiquitin mediated proteolysis were over-represented during the initial stage of ripening, with ABC transporters and sulfur metabolism pathways active during the middle stages and ABC transporters and spliceosome enriched in the final stages of ripening. Several miRNAs and their targets serving as potential regulators in L. barbarum fruit ripening were identified using quantitative reverse transcription polymerase chain reaction. The miRNA-target interactions were predicted for L. barbarum ripening regulators including miR156/157 with LbCNR and LbWRKY8, and miR171 with LbGRAS. Additionally, regulatory interactions potentially controlling fruit quality and nutritional value via sugar and secondary metabolite accumulation were identified. These include miR156 targeting of fructokinase and 1-deoxy-D-xylulose-5-phosphate synthase and miR164 targeting of beta-fructofuranosidase. In sum, valuable information revealed by small RNA sequencing in this study will provide a solid foundation for uncovering the miRNA-mediated mechanism of fruit ripening and quality in this nutritional food.
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PMID:Identification and characterization of miRNAs in ripening fruit of Lycium barbarum L. using high-throughput sequencing. 2644 86


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