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Query: UNIPROT:P62988 (Ubiquitin)
 4,326 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ubiquitin is an omnipresent protein found in all eukaryotes so far analysed. It is involved in several important processes, including protein turnover, chromosome structure and stress response. Parsley (Petroselinum crispum) contains at least two active polyubiquitin (ubi4) genes encoding hexameric precursor proteins. The deduced amino acid sequences of the ubiquitin monomers are identical to one another and to ubiquitin sequences from several other plant species. Analysis of the promoter region of one ubi4 gene revealed putative regulatory elements. In parsley plants, the ubi4 mRNAs were the predominant ubiquitin mRNAs and were present at comparable levels in all plant organs tested. In cultured parsley cells, high levels of ubiquitin gene expression remained unaffected by heat shock, elicitor or light treatment.
Plant Mol Biol 1993 Feb
PMID:Polyubiquitin gene expression and structural properties of the ubi4-2 gene in Petroselinum crispum. 838 52

We have isolated and determined DNA sequence for the 5'-flanking regions of three Arabidopsis thaliana polyubiquitin genes, UBQ3, UBQ10, and UBQ11. Comparison to cDNA sequences revealed the presence of an intron in the 5'-untranslated region at the same position immediately upstream of the initiator methionine codon in each of the three genes. An intron at this position is also present in two sunflower and two maize polyubiquitin genes. An intron is also found in the 5'-untranslated regions of several animal polyubiquitin genes, although the exact intron position is not conserved among them, and none are in the same position as those in the higher plant polyubiquitin genes. Chimeric genes containing the 5'-flanking regions of UBQ3, UBQ10, and UBQ11 in front of the coding regions for the reporter enzyme Escherichia coli beta-glucuronidase (GUS) were constructed. When introduced transiently into Arabidopsis leaves via microprojectile bombardment, all resulted in readily detectable levels of GUS activity that were quantitatively similar. The introns of UBQ3 and UBQ10 in the corresponding promoter fragments were removed by replacement with flanking cDNA sequences and chimeric genes constructed. These constructs resulted in 2.5- to 3-fold lower levels of marker enzyme activity after transient introduction into Arabidopsis leaves. The UBQ10 promoter without the 5' intron placed upstream of firefly luciferase (LUX) resulted in an average of 3-fold lower LUX activity than from an equivalent construct with the UBQ10 intron. A UBQ3 promoter cassette was constructed for the constitutive expression of open reading frames in dicot plants and it produced readily detectable levels of GUS activity in transient assays.
Plant Mol Biol 1993 Mar
PMID:The intron of Arabidopsis thaliana polyubiquitin genes is conserved in location and is a quantitative determinant of chimeric gene expression. 838 9

We isolated a rice cDNA clone encoding the ubiquitin protein fused to a ribosomal protein. This clone encodes a single ubiquitin polypeptide and extension protein of 53 amino acids. This extension protein shows a high degree of homology with those of the yeast ubil or ubi2 gene, both of which encode the same protein. Northern blot analysis suggested that the expression pattern of this gene is more similar to other ribosomal protein genes not linked to ubiquitin protein than to the polyubiquitin gene.
Plant Mol Biol 1993 Apr
PMID:Isolation and characterization of a rice cDNA which encodes a ubiquitin protein and a 52 amino acid extension protein. 838 48

We have developed a genetic screen of the yeast Saccharomyces cerevisiae to identify genes that act to coordinate DNA replication so that each part of the genome is copied exactly once per cell cycle. A mutant was recovered in this screen that accumulates aberrantly high DNA contents but does not complete a second round of synthesis. The mutation principally responsible for this phenotype is in the DOA4 gene, which encodes a ubiquitin hydrolase, one of several yeast genes that encode enzymes that can remove the signalling polypeptide ubiquitin hydrolase, one of several yeast genes that encode enzymes that can remove the signaling polypeptide ubiquitin from its covalently linked conjugated forms. DOA4 is nonessential, and deleting this gene causes uncoordinated replication. Overreplication does not occur in cells with limiting amounts of Cdc7 protein kinase, suggesting that entry into S phase is required for this phenotype. The DNA formed in doa4 mutants is not highly unusual in the sense that mitotic recombination rates are normal, implying that a high level of repair is not induced. The temperature sensitivity of doa4 mutations is partially suppressed by extra copies of the polyubiquitin gene UB14, but overreplication still occurs in the presence of this suppressor. Mutations in DOA4 cause loss of the free ubiquitin pool in cells under heat stress conditions, and extra copies of UB14 restore this pool without restoring coordination of replication. We conclude that a ubiquitin-mediated signaling event directly involving the ubiquitin hydrolase encoded by DOA4 is needed in S. cerevisiae to prevent uncoordinated DNA replication.
Mol Cell Biol 1996 Apr
PMID:Coordinating DNA replication to produce one copy of the genome requires genes that act in ubiquitin metabolism. 865 9

The polyubiquitin gene from the mosquito Anopheles gambiae has been cloned and sequenced, and its structure is reported along with sequence analysis results. The gene consists of approximately seven tandem head-to-tail repeat units of the seventy-six amino acid-coding ubiquitin monomer. It is expressed constitutively in larvae, pupae and adults of An. gambiae, as well as in a cell line derived from this mosquito species. A probe made from a DNA fragment containing the coding region of the gene recognizes transcripts of approximately 3.6 kb and 4.4 kb in RNA isolated from all mosquito developmental stages and a unique transcript of approximately 3.0 kb in RNA from the cell line. Single monomeric units of the An. gambiae polyubiquitin gene shared from 75.9% to 85.5% identity at the DNA level with homologous sequences from other organisms ranging from yeast to man. A comparison of individual repeat units of the An. gambiae gene revealed that, in general, the 5' ends of the individual monomers are more highly conserved than the 3' ends. The gene mapped by in situ hybridization on ovarian nurse cell polytene chromosomes to a primary site at division 12C on chromosome 2R and to a secondary site at division 9C on the same chromosome.
Insect Mol Biol 1996 May
PMID:The polyubiquitin gene of the mosquito Anopheles gambiae: structure and expression. 867 61

Perturbations in keratin intermediate filament organization and Mallory body (MB) formation are associated with alcoholic hepatitis. Inducible heat shock proteins (HSPs) are expressed in a variety of liver diseases including alcoholic liver disease. Therefore, we investigated whether heat shock protein induction can lead to MB formation. Mice were primed by a 5-month feeding of griseofulvin (GF) or diethyl 1,4-dehydro-2,4,6-trimethyl-3,5-pyridinedicarboxylate (DDC) followed by drug withdrawal for 1 month. The animals were then subjected to an in vivo heat shock treatment or sham heat treatment. Liver morphology, HSP expression, liver regeneration (PCNA-labeled nuclei), and MB formation were monitored during a 7-day posttreatment period. Numerous MBs developed in the livers of mice exposed to GF or DDC for 5 months, but very few small MBs remained after 1-month withdrawal of either drug. No MBs were found at Day 1 post heat shock, whereas numerous MBs were observed at Day 7. The frequency of PCNA-labeled nuclei increased during the same period. At Day 1 posttreatment, a variable liver centrilobular necrosis was observed accompanied by a prominent increase in HSP-25 and HSP70 expression, but HSP-90 expression was not increased. In drug-primed mouse liver, a heat shock treatment induces the expression of specific HSPs prior to the formation of MBs, indicating that HSP expression may play a role in the pathogenesis of MB formation. We speculate that this role is through the protein unfolding function of HSP, which leads to the aggregation of the cytokeratins to form MBs as well as to polyubiquitin binding to these proteins in a manner analogous to amyloid formation.
Exp Mol Pathol 1995 Aug
PMID:Heat shock in vivo induces Mallory body formation in drug primed mouse liver. 875 55

A dominant insertional P-element mutation enhances position-effect variegation in Drosophila melanogaster. The mutation is homozygous, viable, and fertile and maps at 64E on the third chromosome. The corresponding gene was cloned by transposon tagging. Insertion of the transposon upstream of the open reading frame correlates with a strong reduction of transcript level. A transgene was constructed with the cDNA and found to have the effect opposite from that of the mutation, namely, to suppress variegation. Sequencing of the cDNA reveals a large open reading frame encoding a putative ubiquitin-specific protease (Ubp). Ubiquitin marks various proteins, frequently for proteasome-dependent degradation. Ubps can cleave the ubiquitin part from these proteins. We discuss the link established here between a deubiquitinating enzyme and epigenetic silencing processes.
Mol Cell Biol 1996 Oct
PMID:The dose of a putative ubiquitin-specific protease affects position-effect variegation in Drosophila melanogaster. 881 85

We have investigated the genomic organization of Entamoeba histolytica ubiquitin and looked for the occurrence of a ubiquitin-conjugating system in this organism. Southern blots indicated the presence of > or = 5 ubiquitin-coding regions. One of these, EhUBI1, was cloned and sequenced and found to correspond to a monoubiquitin gene; as shown by a polymerase chain reaction, E. histolytica lacked polyubiquitin genes altogether. Blots of poly(A)+ RNA from exponentially-growing trophozoite cultures exhibited five ubiquitin transcripts, the most prominent and smallest of which corresponded to EhUBI1 mRNA. Expression of the ubiquitin genes was not influenced by heat shock. Although the predicted amino acid sequence of the ubiquitin from E. histolytica differs significantly (in 7-9 amino acid residues) from that of yeast and animals, expression of the coding sequence of EhUBI1 suppressed the heat-sensitive phenotype of a polyubiquitin gene-deficient yeast mutant. In correlation, trophozoite extract catalyzed an ATP-dependent conjugation of radioiodinated bovine ubiquitin to trophozoite proteins. The latter data indicate that E. histolytica contains a functional ubiquitin-conjugating system.
Mol Biochem Parasitol 1996 Nov 12
PMID:Characterization of ubiquitin genes and -transcripts and demonstration of a ubiquitin-conjugating system in Entamoeba histolytica. 894 52

Ubiquitin gene expression following transient forebrain ischemia in the rat was analyzed by three probes which were specific for UbC, UbB and UbS30 mRNA. According to the in situ hybridization studies, each type of ubiquitin gene expression decreased at 30 min of reperfusion following 20 min of forebrain ischemia, thereafter increased, and then reached a peak at 4-6 h, both in the cortex and hippocampus. These changes returned to the control level after 24-48 h of recirculation. Among the three ubiquitin transcripts, changes in UbC expression were more marked in the hippocampus, and persistent expression of UbC transcripts in the CA1 and CA3 regions was observed at 24 h of reperfusion. With dot-blot analysis, significant increases in the UbC transcripts were noted at 4 h of reperfusion in the hippocampus, and at 6 h in the cortex following 20 min of ischemia. These results suggest that changes in UbC expression might be a good indicator of ischemic stress.
Brain Res Mol Brain Res 1996 Mar
PMID:Ubiquitin gene expression following transient forebrain ischemia. 896 46

Levels of the tumor suppressor protein p53 are normally quite low due in part to its short half-life. p53 levels increase in cells exposed to DNA-damaging agents, such as radiation, and this increase is thought to be responsible for the radiation-induced G1 cell cycle arrest or delay. The mechanisms by which radiation causes an increase in p53 are currently unknown. The purpose of this study was to compare the effects of gamma and UV radiation on the stability and ubiquitination of p53 in vivo. Ubiquitin-p53 conjugates could be detected in nonirradiated and gamma-irradiated cells but not in cells which were UV treated, despite the fact that both treatments resulted in the stabilization of the p53 protein. These results demonstrate that UV and gamma radiation have different effects on ubiquitinated p53 and suggest that the UV-induced stabilization of p53 results from a loss of p53 ubiquitination. Ubiquitinated forms of p21, an inhibitor of cyclin-dependent kinases, were detected in vivo, demonstrating that p21 is also a target for degradation by the ubiquitin-dependent proteolytic pathway. However, UV and gamma radiation had no effect on the stability or in vivo ubiquitination of p21, indicating that the radiation effects on p53 are specific.
Mol Cell Biol 1997 Jan
PMID:Ubiquitination of p53 and p21 is differentially affected by ionizing and UV radiation. 897 16


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