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

Ubiquitin, a protein thought to be involved in the ATP-dependent non-lysosomal degradation of abnormal proteins, has already been identified as a component of neurofibrillary tangles in Alzheimer's disease. We have examined ubiquitin immunoreactivity in a unique collection of brains from 16 ex-boxers including 11 with dementia pugilistica. Neurofibrillary tangles of dementia pugilistica were labelled with an affinity purified antiserum to ubiquitin, and BF10, a monoclonal antibody to a neurofilament epitope.
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PMID:Neurofibrillary tangles in dementia pugilistica are ubiquitinated. 185 Apr 50

Ubiquitin (Ubq), a 76-amino acid (aa) protein, is found in all eukaryotic organisms and is one of the most conserved proteins so far studied. It is implicated in many cellular processes. The Ubq-encoding genes (ubq) are generally present as a multigene family. In flax, we have estimated that this multigene family contains at the most ten members. The initial flax ubq sequences were isolated from a flax genomic library in lambda EMBL4 using a heterologous Arabidopsis thaliana ubq probe. An 916-bp fragment from one of the phage clones was subcloned and sequenced. The aa sequence derived from the nucleotide sequence of this fragment is identical to that of other plant Ubqs. This fragment was then used to isolate additional flax ubq clones. In all, eleven phage lambda clones, which represent six members of the gene family, were restriction-mapped and characterized. These six members are represented as three monomers, three poly-Ubqs, one hexamer and two tetramers. They can be present at either a single locus (two of the monomers and one of the poly-Ubqs) or at two loci (the remaining three genes). The other four members of the family are yet to be cloned and characterized.
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PMID:The ubiquitin-encoding multigene family of flax, Linum usitatissimum. 185 Jul 10

Ubiquitin (Ub) conjugates to Saccharomyces cerevisiae iso-2-cytochrome c were formed in vitro in a rabbit reticulocyte extract (Fraction II). In the presence of ubiquitin-aldehyde, used to inhibit ubiquitin-protein isopeptidases in Fraction II, mono-, di-, and triubiquitinated cytochrome c conjugates accumulated in a 1.2:1.0:0.2 molar ratio. CNBr digestions showed that, in all three conjugates, Ub attachment was within the first 73 amino acids of the cytochrome c. For the two most abundant conjugates, this region was further narrowed to the first 30 residues by peptide mapping with Staphylococcus aureus V8 protease. N-terminal protein sequencing identified Lys-13 as the major ubiquitination site in each conjugate. For di- and triubiquitinated iso-2-cytochrome c, this suggested that Ub2 and Ub3 multiubiquitin chains extend from Lys-13. This conclusion was supported by a variation of protein sequencing in which polypeptides recovered after Edman degradation were analyzed to determine at which cycle(s) radiolabeled Ub or Ubn was cleaved from the conjugate. Because of the sensitivity afforded by the use of 125I-Ub in this "stutter-step" sequencing method, minor ubiquitination at Lys-8 also was detected. Thus, Ub2-iso-2-cytochrome c conjugates contain mostly Ub2 at Lys-13 with a small fraction of conjugates having single Ubs on 2 residues, Lys-8 and Lys-13. Similarly, Ub3-iso-2-cytochrome c predominantly has a Ub3 chain on Lys-13, although minor species with combinations of Ub1 and Ub2 distributed on Lys-8 and Lys-13 also may be present. This specificity is discussed in the context of iso-2-cytochrome c structure.
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PMID:The structures of ubiquitin conjugates of yeast Iso-2-cytochrome c. 185 Nov 66

Ubiquitin-conjugating enzymes (E2s), which participate in the post-translational conjugation of ubiquitin to proteins, are encoded by a multigene family in the yeast Saccharomyces cerevisiae. E2s function in a variety of cellular activities including intracellular proteolysis, DNA repair, sporulation, and cell cycle traverse. Here, we report the cloning and characterization of a new member of the yeast UBC gene family, UBC8. UBC8 encodes a 206-amino acid protein containing a highly acidic carboxyl terminus. The primary structure of the protein is similar to that of all other known E2s, with the highest homology being to the E2 (23 kDa) of wheat germ. Haploid strains in which the UBC8 gene is disrupted are viable, and the disruption does not produce any obvious phenotype. The UBC8 protein, produced in Escherichia coli, forms thiol ester adducts with ubiquitin and, apparently, diubiquitin, but does not transfer ubiquitin to histones.
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PMID:Cloning and characterization of a Saccharomyces cerevisiae gene encoding a new member of the ubiquitin-conjugating protein family. 186 73

The heat shock/stress response is characterized by the induction of several highly evolutionarily conserved proteins during thermal stress, chemical stress, or glucose starvation. It has recently been recognized that members of the stress protein family are synthesized constitutively and subserve functions that are critical to protein folding during intracellular transport. In this study we examined the expression of heat shock/stress proteins in human mononuclear phagocytes, cells dependent on intracellular transport for Ag processing, Ag presentation, generation of reactive oxygen intermediates, and secretion of proinflammatory and antiinflammatory polypeptides. The results indicate that there are distinct patterns in expression of individual members of the highly homologous SP70, SP90, and ubiquitin gene families during different stress states. There is a marked increase in expression of the heat-inducible form of SP70 and SP90 in human monocytes during heat shock. Expression of GRP 78/BiP and GRP 94 increases predominantly during glucose starvation but also increases during heat shock. Ubiquitin gene expression increases during both heat shock and glucose starvation. There is no change in synthesis of the constitutive form of SP 70 or of the ubiquitin activating enzyme E1 during heat shock or glucose starvation. Synthesis of the constitutive form of SP 70 and novel SP 90-like polypeptides increase during endotoxin-mediated inflammatory activation. One intracellular transport process of the mononuclear phagocyte, secretion of specific proinflammatory and antiinflammatory polypeptides, is affected by glucose starvation and by heat shock.
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PMID:Expression of stress proteins in human mononuclear phagocytes. 188 Apr 18

Four ubiquitin-peptide extensions prepared as cloned products in E. coli were tested as casein kinase II substrates. Two extensions containing the sequence Ser-Glu-Glu-Glu-Glu-Glu were readily phosphorylated by partially purified rabbit reticulocyte casein kinase II. The other two fusion proteins, which lack a consensus phosphorylation site for casein kinase II, did not serve as substrates under identical reaction conditions. Native ubiquitin was not phosphorylated by reticulocyte casein kinase II, nor have we observed its phosphorylation in crude extracts from HeLa cells, mouse liver, or Xenopus eggs. Ubiquitin's apparent lack of phosphorylatable residues coupled with its remarkable heat stability and rapid migration on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels make the protein an attractive carrier for carboxyl-terminal peptides containing specific phosphorylation sites. Such ubiquitin extension proteins should prove valuable as protein kinase substrates.
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PMID:The use of ubiquitin-peptide extensions as protein kinase substrates. 196 25

Ubiquitin is involved in cell-cycle control and DNA replication through a specific proteolytic pathway. Our previous studies demonstrated selected higher expression of a gene encoding ubiquitin-ribosomal protein S27a in poorly differentiated colon carcinoma cell lines. In this study, we evaluated this ubiquitin hybrid protein gene expression in surgical specimens of colon cancers. Northern blot analysis showed that ubiquitin hybrid protein messenger RNA was overexpressed in primary colon cancers compared with adjacent normal colon mucosae in 17 of 20 patients. Dot blot analysis of RNA of 27 tumor samples revealed significantly greater expression in higher Dukes' stage primary colon tumors and liver metastases. These data imply that protein translation machinery is highly activated during progression and metastasis of colon tumors, and that ubiquitin hybrid protein may be useful as a marker of biological aggressiveness.
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PMID:Ubiquitin hybrid protein gene expression during human colon cancer progression. 200 61

In eukaryotes, both natural and engineered fusions of ubiquitin to itself or other proteins are cleaved by processing proteases after the last (Gly76) residue of ubiquitin. Using the method of sib selection, and taking advantage of the fact that bacteria such as Escherichia coli lack ubiquitin-specific enzymes, we have cloned a gene, named UBP1, of the yeast Saccharomyces cerevisiae that encodes a ubiquitin-specific processing protease. With the exception of polyubiquitin, the UBP1 protease cleaves at the carboxyl terminus of the ubiquitin moiety in natural and engineered fusions irrespective of their size or the presence of an amino-terminal ubiquitin extension. These properties of UBP1 distinguish it from the previously cloned yeast protease YUH1, which deubiquitinates relatively short ubiquitin fusions but is virtually inactive with longer fusions such as ubiquitin-beta-galactosidase. The amino acid sequence of the 809-residue UBP1 lacks significant similarities to other known proteins, including the 236-residue YUH1 protease. Null ubp1 mutants are viable, and retain the ability to deubiquitinate ubiquitin-beta-galactosidase, indicating that the family of ubiquitin-specific proteases in yeast is not limited to UBP1 and YUH1.
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PMID:Cloning and functional analysis of the ubiquitin-specific protease gene UBP1 of Saccharomyces cerevisiae. 205 Jun 95

We report the autopsy findings of an 81-year-old patient with short-course sporadic amyotrophic lateral sclerosis lasting approximately 5 months. Pathological findings were probably very early. Light microscopy showed abundant eosinophilic Bunina type inclusions widely distributed not only in the motor neurons of the spinal cord and brain stem but also in neurons of the Onuf's and Clarke's nuclei. Fine structural study revealed that the inclusions seen in the Clarke's nuclei were identical to Bunina bodies observed in anterior horn cells. A direct connection between axonal swelling and perikaryon was often seen in the facial and hypoglossal nuclei and in the spinal cord. Ubiquitin-positive Lewy body-like inclusions and central chromatolysis-like changes were also found in the anterior horn cells.
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PMID:Widely distributed Bunina bodies and spheroids in a case of atypical sporadic amyotrophic lateral sclerosis. 205 68

The baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV, which is representative of the MNPV subtype in which the virions may contain many nucleocapsids within a single viral envelope) encodes a protein, v-ubi, that has 76% identity with the eukaryotic protein ubiquitin. Transcriptional mapping indicated that the gene for v-ubi was transcribed during the late phase of viral infection. Two transcriptional start sites potentially encoding v-ubi were identified. Both sites were contained within a sequence motif common to baculovirus late genes. A recombinant virus, AcUbi-beta Gal, encoding a ubiquitin-beta-galactosidase fusion protein was constructed to monitor the temporal regulation of v-ubi gene during viral infection. The fusion protein was expressed maximally at 14-18 hr postinfection, consistent with its classification as a late protein. The amount of ubiquitin-beta-galactosidase fusion protein that accumulated in AcUbi-beta Gal-infected cells by 48 hr postinfection was approximately 14% of the level of beta-galactosidase that was synthesized under control of the polyhedrin promoter. Transcriptional analysis confirmed that synthesis of the fusion protein was directed by the v-ubi gene promoter. AcUbi-beta Gal also produced normal levels of authentic viral ubiquitin message. Southern blot analysis of AcUbi-beta Gal and 15 additional isolates revealed that the fusion sequences had not recombined at the ubiquitin locus. A polyubiquitin gene was isolated and sequenced from Spodoptera frugiperda, a lepidopteran host cell line for AcMNPV. The predicted amino acid sequence of the product of the host gene is identical to animal ubiquitin.
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PMID:Identification of a viral gene encoding a ubiquitin-like protein. 215


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