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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ubiquitin genes provide a model for studying the effects of concerted evolution on the evolution of a family of short repeated sequences. Previous work has demonstrated the occurrence of within-locus concerted evolution and raised the question of the effectiveness of between-locus concerted evolution for ubiquitin repeats. In this study comparative analysis of additional nucleotide sequences of ubiquitin tandem repeats provides further details of within-locus concerted evolution. Moreover, the availability of multiple polyubiquitin loci and ubiquitin fusion loci within a species makes possible the detection of between-locus concerted evolution. These data indicate that concerted evolution is an effective force for homogenizing repeats between, as well as within, loci.
Mol Phylogenet Evol 1993 Dec
PMID:Ubiquitins revisited: further examples of within- and between-locus concerted evolution. 804 84

The foraminifera are one of the last major groups of eukaryotes for which no published DNA sequences exist. DNA sequence of ubiquitin repeat units from 5 foraminifera (representing 3 suborders), a diatom, and a dinoflagellate were characterized using the polymerase chain reaction, cloning, and sequencing. The phylogenetic utility of ubiquitin DNA sequence is discussed in reference to a full eukaryote data base. The foraminifera are possibly a polyphyletic group, whereas the phylogenetic placement of the diatom and the dinoflagellate are congruent with existing hypotheses. The lack of a noneukaryote root and limited phylogenetically informative sequence information indicate that polyubiquitin may not be useful for phylogenetic reconstruction of all eukaryotes.
Mol Mar Biol Biotechnol 1994 Feb
PMID:Phylogenetic utility of ubiquitin DNA sequence from 3 marine protist lineages. 805 61

In Arabidopsis thaliana L., accumulation of abscisic acid (ABA) began to increase 2 h after plants had been subjected to dehydration stress and reached maximum levels after 10 h. Differential hybridization was used to isolate 26 Arabidopsis cDNAs with gene expression induced by a 1 h dehydration treatment. The cDNA clones were classified into 16 groups based on Southern blot hybridization, and named ERD (early-responsive to dehydration) clones. Partial sequencing of the cDNA clones revealed that three ERDs were identical to those of HSP cognates (Athsp70-1, Athsp81-2, and ubiquitin extension protein). Dehydration stress strongly induced the expression of genes for the three ERDs, while application of ABA, which is known to act as a signal transmitter in dehydration-stressed plants, did not significantly affect the ERD gene expression. This result suggests that these HSP cognates are preferentially responsive to dehydration stress in A. thaliana, and that signaling pathways for the expression of these genes under conditions of dehydration stress are not mainly mediated by ABA. We also discuss the possible functions of these three ERD gene products against dehydration stress.
Plant Mol Biol 1994 Aug
PMID:Cloning of cDNAs for genes that are early-responsive to dehydration stress (ERDs) in Arabidopsis thaliana L.: identification of three ERDs as HSP cognate genes. 807 96

We characterized three genes encoding different E2-type ubiquitin carrier proteins involved in the ubiquitin-mediated proteolytic pathway: UbcAt3 shows homologies to the yeast CDC34 gene and Ub-cAt4a and UbcAt4b are two different genes homologous to the Ubc1/4/5 subfamily in yeast. Their accumulation was analysed and compared with that of the different families encoding polyubiquitins, as well as the monoubiquitin fusion protein, which is considered as a marker for cell division, during various developmental stages including G0/S transition and senescence of higher plant cells. Our results imply that these Ubc genes are under the control of complex mechanisms, and are differentially regulated, but not necessarily co-regulated with ubiquitin genes. Even the closely related UbcAt4a and UbcAt4b genes of the same multigene subfamily are controlled by distinct regulatory mechanisms.
Mol Gen Genet 1994 Sep 01
PMID:Differential expression of several E2-type ubiquitin carrier protein genes at different developmental stages in Arabidopsis thaliana and Nicotiana sylvestris. 807 82

In the present paper we report the isolation and characterization of the sequence of two genomic DNA fragments coding for the histone H2A of Trypanosoma cruzi. An analysis of the predicted amino acid sequence shows the presence of the amino-terminal motif characteristic of the H2A histones proteins and the Lys-Lys motif reported to be the site for the ubiquitin attachment. Southern blots of total parasite DNA probed with the H2A sequence suggested that the T. cruzi histone H2A gene is encoded in two independent gene clusters. The molecular karyotyping of the parasite indicated that these two clusters locate in a single chromosome of about 700 kb in length. The T. cruzi H2A mRNA is polyadenylated as are the basal histone mRNAs of higher eukaryotes and the histone mRNAs of yeast. By polymerase chain reaction amplification and sequencing and by S1 mapping we determined respectively the 5' and 3' end of the gene showing that the miniexon is added to the mRNA 71 nucleotides upstream of the ATG initiation codon and that the polyadenylation site locates in nucleotide position 773-775 close to invert repeats.
Mol Biochem Parasitol 1994 Mar
PMID:Isolation and characterization of the gene encoding histone H2A from Trypanosoma cruzi. 807 13

Eukaryotic proteins are targeted for degradation by covalent ligation of multiubiquitin chains. In these multiubiquitin chains, successive ubiquitins are linked by an isopeptide bond involving the side chain of Lys48 and the carboxyl group of the C-terminus (Gly76). The crystal structure of a tetraubiquitin chain (Ub4) has been determined and refined at 2.4 A resolution. The molecule exhibits both translational and 2-fold rotational symmetry; each pair of (rotationally symmetric) ubiquitin molecules in Ub4 is related to the next pair by a simple translation. The 2-fold symmetry in each pair of ubiquitin molecules is quite different from the 2-fold symmetry observed in the previously determined structure of isolated diubiquitin. There are multiple hydrophilic contacts among the four ubiquitin molecules, but the hydrophobic surface formed in the middle of diubiquitin is not seen. The structure of the tetraubiquitin chain demonstrates how a multiubiquitin chain of any length can be formed.
J Mol Biol 1994 Feb 18
PMID:Structure of tetraubiquitin shows how multiubiquitin chains can be formed. 810 44

A genomic clone encoding the potato homolog of the yeast ubiquitin-ribosomal protein fusion gene ubi3 was isolated and characterized. Chimeric genes containing the ubi3 promoter (920 bp of 5' to the ubiquitin start codon) were constructed in which the reporter gene beta-glucuronidase (GUS) was either fused directly to the promoter, or introduced as a translational fusion to the ubiquitin-coding region. After introduction into the potato by Agrobacterium-mediated transformation, GUS activities were measured in leaves and in tubers of transgenic clones. GUS activity was 5- to 10-fold higher in clones expressing the ubiquitin-GUS translational fusion than in clones containing GUS fused directly to the ubi3 promoter. For both types of constructs, GUS activity was highest in meristematic leaves and declined during leaf expansion, then rose again to near the meristematic levels during senescence. GUS activity in tubers was similar to that in young leaves. In contrast to the native ubi3 genes, the chimeric ubi3-GUS transgenes were not activated in the tuber by wounding.
Plant Mol Biol 1994 Jan
PMID:Isolation of a ubiquitin-ribosomal protein gene (ubi3) from potato and expression of its promoter in transgenic plants. 811 Oct 11

A subtidal seaweed collected in antarctic waters, Plocamium cartilagineum (L. Dix.), displayed induction of mRNAs encoding the 70 kDa heat shock protein (HSP70) and the ubiquitin polyprotein (UBI) when incubated at 5 degrees C. Maximal induction of HSP70 mRNA was observed when the alga was incubated at 10 degrees C for 1 h. Incubations at higher temperatures or for longer periods reduced the amount of HSP70 mRNA detected. Incubations at 20 degrees C or greater resulted in cell death. These data indicate that dispite the unusually low temperature of induction, this macrophyte exhibits a heat shock response similar to that of other organisms at temperatures 5 to 10 degrees C above usual growth conditions.
Plant Mol Biol 1994 Jan
PMID:The heat shock response of an antarctic alga is evident at 5 degrees C. 811 Oct 21

The only gene in Drosophila melanogaster for a 52 amino acid ribosomal protein (CEP52) is fused to a ubiquitin coding sequence. This study examines expression and proteolytic processing of the encoded fusion protein. Most antibody preparations made against a portion of human CEP52 readily detect the insect protein. The size of the immunoreactive polypeptide indicates that CEP52 is cleaved from ubiquitin and this apparent proteolytic processing was confirmed by amino-terminal sequence analysis of CEP52 isolated by two-dimensional gel electrophoresis. Ribosomes from embryonic, larval and adult Drosophila melanogaster contain equivalent amounts of CEP52 and the protein is associated with the large ribosomal subunit. Stained two-dimensional gels indicate that the quantity of CEP52 associated with ribosomes is similar to that of other ribosomal proteins of corresponding size. A previous investigation had indicated the possibility of intact ubiquitin-CEP52 fusion protein in Dictyostelium discoideum, Saccharomyces cerevisiae and Drosophila melanogaster. One of three antibody preparations used in this study of insect CEP52 reacts with a 40S subunit protein that is the correct size to be the uncleaved fusion protein. However, the putative fusion protein does not react with ubiquitin antibodies and has negligible positive charge at pH5, demonstrating that it is not unprocessed ubiquitin-CEP52.
Insect Biochem Mol Biol 1994 Feb
PMID:The smaller protein formed as a ubiquitin fusion in Drosophila is processed from ubiquitin and found on the 60S ribosomal subunit. 811 27

The wild-type p53 gene product plays an important role in the control of cell proliferation, differentiation, and survival. Altered function is frequently associated with changes in p53 stability. We have studied the role of the ubiquitination pathway in the degradation of p53, utilizing a temperature-sensitive mutant, ts20, derived from the mouse cell line BALB/c 3T3. We found that wild-type p53 accumulates markedly because of decreased breakdown when cells are shifted to the restrictive temperature. Introduction of sequences encoding the human ubiquitin-activating enzyme E1 corrects the temperature sensitivity defect in ts20 and prevents accumulation of p53. The data therefore strongly indicate that wild-type p53 is degraded intracellularly by the ubiquitin-mediated proteolytic pathway.
Mol Cell Biol 1994 Mar
PMID:Accumulation of p53 in a mutant cell line defective in the ubiquitin pathway. 811 31


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