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

The stress-induced expression of four different ubiquitin-encoding cDNAs was characterized in potato tuber tissue. The four clones exhibited differences in both structure and expression. The first cDNA encoded a single ubiquitin unit fused to an 80 amino acid ribosomal extension protein identical to the extension protein from tomato. Accumulation of the fusion transcript was induced by injury or ethylene, but not by heat shock. The three remaining ubiquitin cDNAs encoded polyubiquitins with 6 to 7 ubiquitin repeats. The first polyubiquitin gene was induced by injury, heat, or ethylene treatments. The second was induced also by injury or heat, with limited ethylene-dependent accumulation of transcript. Transcript levels of the third polyubiquitin gene were highest in control tubers and decreased markedly with injury, heat shock, or ethylene treatment. The data demonstrate the independent regulation of the different members of the ubiquitin gene family in response to stress and exogenous ethylene.
Plant Mol Biol 1992 Oct
PMID:Expression of stress-responsive ubiquitin genes in potato tubers. 132 70

Ubiquitin is a small, 8 kD protein found in all eukaryotic cells. It is involved in a wide variety of regulatory roles within the cell, including gene expression, ribosome biosynthesis, receptor expression, and the stress response. The best understood of these is that of ubiquitin-mediated proteolysis, in which ubiquitin is covalently attached to specific protein target substrates that are then recognized and degraded by a high molecular weight protease.
Am J Respir Cell Mol Biol 1992 Nov
PMID:Ubiquitin-mediated protein modification and degradation. 132 65

We have characterized a second T. brucei polyubiquitin gene (UbB) that is highly similar in the coding and flanking regions to a previously described T. brucei polyubiquitin gene (UbA). However, UbB differs from UbA in 2 respects: (1) the predicted carboxy-terminal amino acid of UbB is methionine, as opposed to leucine in UbA, and (2) UbB contains approximately 13 ubiquitin repeats, as opposed to approximately 30 repeats in UbA. In Southern blots of intact T. brucei DNA separated by pulsed field gel electrophoresis, the polyubiquitin sequences have been shown to reside on band 19, which may contain 3 chromosomes. Three experiments that target a neomycin-resistance gene to the polyubiquitin locus demonstrate a one-to-one ratio of polyubiquitin 3-flanking sequences, which suggests that UbA and UbB are alleles rather than duplications. Four additional strains of T. brucei and one strain of T. equiperdum show variation in their polyubiquitin gene size, suggesting that this is a common polymorphism.
Mol Biochem Parasitol 1992 Oct
PMID:Allelic polymorphism of the Trypanosoma brucei polyubiquitin gene. 133 86

A lambda gt 11 cDNA library, constructed from poly(A)+ mRNA isolated from Avena fatua aleurone layers incubated with 1 microM gibberellin A1 (GA1) for 4 days, was screened with an anti-idiotypic antiserum raised against the GA-specific monoclonal antibody MAC 182. One positive clone was isolated, sequenced and shown to encode a tetraubiquitin based on the deduced amino acid sequence. This polyubiquitin cDNA exhibited a high degree of homology to a cloned wheat hexaubiquitin in its 3'-non-coding region. Analysis of total RNA isolated from A. fatua aleurone layers, treated without or with a range of concentrations of GA1 from 10(-11) to 10(-6) M, by northern blotting using the cDNA probe revealed 8 different ubiquitin-containing transcript classes all of which are constitutively expressed in aleurone and are regulated by GA1.
Plant Mol Biol 1992 Nov
PMID:cDNA cloning of a tetraubiquitin gene, and expression of ubiquitin-containing transcripts, in aleurone layers of Avena fatua. 133 96

A pulse treatment of embryos of Norway spruce with cytokinin suppresses germinative development and induces the coordinate formation of adventitious buds from subepidermal cell layers. To analyse the patterns of gene expression associated with germination and the alterations induced by the bud induction treatment, we have isolated cDNA clones corresponding to genes that are differentially expressed in cytokinin-treated and untreated in vitro germinating embryos. One category of 14 clones hybridized to transcripts that were abundant specifically during germination. The expression of 8 of these genes was reduced by the bud induction treatment. Four clones, including one identified as a histone H2A gene, recognized transcripts that showed an increased abundance in bud-induced versus in vitro germinating embryos. A second category of 13 clones hybridized to transcripts that increased in abundance during post-germinative development of the seedling. Among these a subset of 8 clones, including an alpha-tubulin clone, corresponds to genes suppressed by the bud induction treatment, whereas 5 clones, including a gene with sequence similarity to polyubiquitin, were unaffected by the treatment. One clone hybridized to a message abundant in the seed, during early germination as well as in the vegetative bud, and showed 60% partial sequence identity to a barley (1----3)-beta-glucanase gene. Genes expressed exclusively in bud-induced or in vitro germinating embryos were not found. The results show that a major difference in gene expression between treated and untreated embryos is related to the shift from extensive cell proliferation to elongation and differentiation that occurs at the transition from germination to post-germinative development, and which is suppressed in the bud-induced embryos.
Plant Mol Biol 1992 Feb
PMID:Differential gene expression during germination and after the induction of adventitious bud formation in Norway spruce embryos. 137 81

Two ubiquitin genes, designated UbB1 and UbB2, were isolated from a sunflower genomic library. They encode polyubiquitin transcripts corresponding to six repeats of the monomer. Northern blot analysis identified several different transcript size classes: both UbB1 and UbB2 transcripts are found in the most abundant 1.6 kb class. In contrast to the previously isolated UbF transcript which is present at high levels in flowers, UbB1 and UbB2 are expressed constitutively at low levels in different tissues. The levels of the two transcripts increase after heat stress. The two genes exhibit strong homology suggesting that they may result from duplication and conversion. Surprisingly, UbB1 gene shows structural similarities with the chicken ubiquitin heat shock gene, in particular the presence of an intron located just in front of the first ATG.
Plant Mol Biol 1991 Sep
PMID:Structure and expression of sunflower ubiquitin genes. 165 59

An in planta induced gene of Phytophthora infestans (the causal organism of potato late blight) was selected from a genomic library by differential hybridization using labelled cDNA derived from poly(A)+ RNA of P. infestans grown in vitro and labelled cDNA made from potato-P. infestans interaction poly(A)+ RNA as probes. Sequence analysis showed that the gene codes for ubiquitin, a highly conserved protein which plays an important role in several cellular processes. The structure of the polyubiquitin gene (designated ubi3R) is consistent with the structure of other known polyubiquitin genes. It consists of three repeats in a head-to-tail arrangement without intervening sequences, each encoding a ubiquitin unit of 76 amino acids. The last ubiquitin unit is followed by an extra asparagine residue at the carboxy-terminal end. Northern and Southern blot analyses revealed that the polyubiquitin gene is a member of a multigene family, all genes of which show induced expression in planta.
Plant Mol Biol 1991 Oct
PMID:An in planta induced gene of Phytophthora infestans codes for ubiquitin. 165 13

The genome of Tetrahymena pyriformis has been shown to contain a ubiquitin multigene family consisting of several polyubiquitin genes and at least one ubiquitin fusion gene. We report here the isolation and characterization of one genomic clone (pTU11), that encodes a ubiquitin extension protein. A comparison of the predicted amino acid sequence of the ubiquitin extension protein gene of T. pyriformis with those from other organisms indicated a high degree of homology. However, the Tetrahymena ubiquitin extension protein contains 53 and not 52 amino acids. This feature is different from all ubiquitin 52-amino-acid extension protein genes thus far sequenced. Furthermore, we found an array of four cysteine residues similar to those found in nucleic acid binding proteins. Also, the C-terminal sequence possesses a conserved motif which may represent a nuclear translocation signal. The ubiquitin 53-amino-acid extension protein gene encodes the smallest class of ubiquitin mRNAs in T. pyriformis.
Mol Gen Genet 1991 Nov
PMID:Molecular cloning and expression of a Tetrahymena pyriformis ubiquitin fusion gene coding for a 53-amino-acid extension protein. 166 May 64

Ubiquitin is ubiquitous in all eukaryotes and its amino acid sequence shows extreme conservation. Ubiquitin genes comprise direct repeats of the ubiquitin coding unit with no spacers. The nucleotide sequences coding for 13 ubiquitin genes from 11 species reported so far have been compiled and analyzed. The G + C content of codon third base reveals a positive linear correlation with the genome G + C content of the corresponding species. The slope strongly suggests that the overall G + C content of codons of polyubiquitin genes clearly reflects the genome G + C content by AT/GC substitutions at the codon third position. The G + C content of ubiquitin codon third base also shows a positive linear correlation with the overall G + C content of coding regions of compiled genes, indicating the codon choices among synonymous codons reflect the average codon usage pattern of corresponding species. On the other hand, the monoubiquitin gene, which is different from the polyubiquitin gene in gene organization, gene expression, and function of the encoding protein, shows a different codon usage pattern compared with that of the polyubiquitin gene. From comparisons of the levels of synonymous substitutions among ubiquitin repeats and the homology of the amino acid sequence of the tail of monomeric ubiquitin genes, we propose that the molecular evolution of ubiquitin genes occurred as follows: Plural primitive ubiquitin sequences were dispersed on genome in ancestral eukaryotes. Some of them situated in a particular environment fused with the tail sequence to produce monomeric ubiquitin genes that were maintained across species. After divergence of species, polyubiquitin genes were formed by duplication of the other primitive ubiquitin sequences on different chromosomes. Differences in the environments in which ubiquitin genes are embedded reflect the differences in codon choice and in gene expression pattern between poly- and monomeric ubiquitin genes.
J Mol Evol 1991 Sep
PMID:Essential factors determining codon usage in ubiquitin genes. 166 81

Ubiquitin is involved in the degradation of denatured proteins in the recovery process after various stresses. To clarify the different responses of the ubiquitin system in the hippocampal neurons after ischemia, we chose 7.5 min of sublethal forebrain ischemia in the rat. After 7.5 min of ischemia, ubiquitin-like immunoreactivity (UIR) in most of the hippocampal pyramidal cells, except for the interneurons, diminished after 3 h of reperfusion, but enhanced UIR and subsequent recovery of UIR were observed in the different hippocampal regions after 24 h of reperfusion. The most prolonged recovery of UIR in the hippocampal cells was observed in the CA1 neurons after 72 h of reperfusion. Immunoblot analysis of the proteins extracted from CA1 region showed that high-mol-wt ubiquitin conjugates (HMWUC) above 40 kDa increased, whereas free ubiquitin and ubiquitinated histone 2A decreased slightly after 4 h and 24 h of reperfusion. At 72 h of reperfusion, HMWUC decreased to the original level and free ubiquitin slightly increased beyond the control level. These results suggested that (1) diminished UIR does not always mean depletion of entire ubiquitin-protein conjugates; (2) even after sublethal ischemia, damaged proteins in the CA1 neurons may increase, and it may take a long time for elimination of these proteins.
Mol Chem Neuropathol 1991 Aug
PMID:Changes in ubiquitin and ubiquitin-protein conjugates in the CA1 neurons after transient sublethal ischemia. 166 59


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