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

A cloned Lytechinus pictus cDNA has been identified, which includes seven direct repeats of a 228 bp sequence encoding ubiquitin and about 450 bp of 3' noncoding sequence. The deduced amino acid sequence is identical to that of ubiquitins of other animals (though repeats 3 and 5 each have single amino acid substitutions at different positions). Southern blot analysis revealed that the sea urchin genome contains a single copy of the polyubiquitin gene, and the number of 228 bp repeat units appears to vary from seven to ten among different alleles; no other ubiquitin coding sequences were detected. The size distribution of polyubiquitin mRNA is polymorphic among different individuals, probably corresponding to the differences in copy number of the repetitive coding sequence. The abundance of cytoplasmic polyubiquitin RNA is constant throughout embryogenesis and is similar in ectoderm, endoderm, and mesoderm cells. The constant prevalence of polyubiquitin mRNA apparently results from a balance between ontogenetic changes in its rate of synthesis and its stability in the presence of actinomycin D. Accumulation of polyubiquitin RNA was not heat shock-inducible during embryogenesis.
Mol Reprod Dev 1991 Feb
PMID:Structure and expression of the polyubiquitin gene in sea urchin embryos. 184 68

Ubiquitin DNA sequences were isolated from the higher plant Arabidopsis thaliana L. by screening a lambda-gt11 genomic library with antibodies raised against oat and human ubiquitin. DNA sequence analysis showed that the predicted protein sequence is 100% conserved with that found in oat and barley and differs by only three residues to that found in animals. This gene (UBQ4) encodes a ubiquitin polyprotein with five repeats contiguously linked with no intervening sequences in the coding region and a C-terminal extension of Ser-Phe. Genomic Southern blot analysis showed that ubiquitin sequences comprise a multigene family of approximately 11 members in Arabidopsis. Northern blot analysis identified at least four transcript size classes, which accumulate in sizes ranging from 800 to 1900 bases. A 5'-specific probe for the UBQ4 gene was used to show that after 2 h heat shock stress, the steady state mRNA level decreased significantly in flowers/buds but not in leaves. The UBQ4 transcript accumulates in a differential manner, accumulating to higher levels in germinating tissue, etiolated tissue, and flowers/buds than in mature leaves, roots, or stems.
Mol Gen Genet 1988 Aug
PMID:Characterization of a polyubiquitin gene from Arabidopsis thaliana. 246 Jul 33

We isolated and characterized two related ubiquitin genes from Drosophila melanogaster, polyubiquitin and UB3-D. The polyubiquitin gene contained 18 repeats of the 228-base-pair monomeric ubiquitin-encoding unit arranged in tandem. This gene was localized to a minor heat shock puff site, 63F, and it encoded a constitutively expressed 4.4-kilobase polyubiquitin-encoding mRNA, whose level was induced threefold by heat shock. To investigate the pattern of expression of the polyubiquitin gene in developing animals, a polyubiquitin-lacZ fusion gene was introduced into the Drosophila genome by germ line transformation. The fusion gene was expressed at high levels in a tissue-general manner at all life stages assayed. The ubiquitin-encoding gene, UB3-D, consisted of one ubiquitin-encoding unit directly fused, in frame, to a nonhomologous tail sequence. The amino acid sequence of the tail portion of the protein had 65% positional identity with that of yeast UBI3 protein, including a region that contained a potential nucleic acid-binding motif. The Drosophila UB3-D gene hybridized to a 0.9-kilobase mRNA that was constitutively expressed, and in contrast to the polyubiquitin gene, it was not inducible by heat shock.
Mol Cell Biol 1988 Nov
PMID:Structure and expression of ubiquitin genes of Drosophila melanogaster. 246 65

Ubiquitin is a multifunctional 76-amino-acid protein which plays critical roles in many aspects of cellular metabolism. In Caenorhabditis elegans, the major source of ubiquitin RNA is the polyubiquitin locus, UbiA. UbiA is transcribed as a polycistronic mRNA which contains 11 tandem repeats of ubiquitin sequence and possesses a 2-amino-acid carboxy-terminal extension on the final repeat. The UbiA locus possesses several unusual features not seen in the ubiquitin genes of other organisms studied to date. Mature UbiA mRNA acquires a 22-nucleotide leader sequence via a trans-splicing reaction involving a 100-nucleotide splice leader RNA derived from a different chromosome. UbiA is also unique among known polyubiquitin genes in containing four cis-spliced introns within its coding sequence. Thus, UbiA is one of a small class of genes found in higher eucaryotes whose heterogeneous nuclear RNA undergoes both cis and trans splicing. The putative promoter region of UbiA contains a number of potential regulatory elements: (i) a cytosine-rich block, (ii) two sequences resembling the heat shock regulatory element, and (iii) a palindromic sequence with homology to the DNA-binding site of the mammalian steroid hormone receptor. The expression of the UbiA gene has been studied under various heat shock conditions and has been monitored during larval moulting and throughout the major stages of development. These studies indicate that the expression of the UbiA gene is not inducible by acute or chronic heat shock and does not appear to be under nutritional or developmental regulation in C. elegans.
Mol Cell Biol 1989 Jan
PMID:UbiA, the major polyubiquitin locus in Caenorhabditis elegans, has unusual structural features and is constitutively expressed. 253 20

The polyubiquitin gene, UB14, of Saccharomyces cerevisiae is regulated by a variety of environmental stresses and physiological conditions. After exposure of rapidly growing yeast cells to DNA-damaging agents (4-nitroquinoline-1-oxide and N-methyl-N'-nitro-N-nitrosoguanidine), intracellular levels of UB14 transcript increased rapidly. Induction of UB14 transcripts occurred within 30 to 60 min of exposure to 4-nitroquinoline-1-oxide in RAD+, rad52, and rad6 repair-deficient yeast strains. In high-density RAD+ cultures, the effect of alkylating agents on UB14 transcript levels is attenuated, in part because of significant increases in the basal level of this message in untreated cells. We also observed that the levels of UB14 transcripts increased significantly when diploid cells were exposed to sporulation conditions. Maximal levels of UB14 transcripts were reached after 6 to 8 h in sporulation medium. Accumulation of UB14 transcripts occurred in a/alpha diploids that undergo meiosis but not in asporogenous alpha/alpha diploids exposed to the same nutritional conditions.
Mol Cell Biol 1988 Mar
PMID:Expression of the yeast UB14 gene increases in response to DNA-damaging agents and in meiosis. 283 62

Ubiquitin is remarkable for its ubiquitous distribution and its extreme protein sequence conservation. Ubiquitin genes comprise direct repeats of the ubiquitin coding unit with no spacers. The nucleotide sequences of several ubiquitin repeats from each of humans, chicken, Xenopus, Drosophila, barley, and yeast have recently been determined. By analysis of these data we show that ubiquitin is evolving more slowly than any other known protein, and that this (together with its gene organization) contributes to an ideal situation for the occurrence of concerted evolution of tandem repeats. By contrast, there is little evidence of between-cluster concerted evolution. We deduce that in ubiquitin genes, concerted evolution involves both unequal crossover and gene conversion, and that the average time since two repeated units within the polyubiquitin locus most recently shared a common ancestor is approximately 38 million years (Myr) in mammals, but perhaps only 11 Myr in Drosophila. The extreme conservatism of ubiquitin evolution also allows the inference that certain synonymous serine codons differing at the first two positions were probably mutated at single steps.
J Mol Evol 1987
PMID:Ubiquitin genes as a paradigm of concerted evolution of tandem repeats. 304 Oct 10

Ubiquitin is a 76-amino-acid protein with a remarkably high degree of conservation between all known sequences. Ubiquitin genes are almost always multicopy in eukaryotes, and often are found as polyubiquitin genes--fused tandem repeats which are coexpressed. Seventeen ubiquitin sequences from the amitochondrial protist Trichomonas vaginalis have been examined here, including an 11-repeat fragment of a polyubiquitin gene. These sequences reveal a number of interesting features that are not seen in other eukaryotes. The predicted amino acid sequences lack several universally conserved residues, and individual units do not always encode identical peptides as is usually the case. On the nucleotide level, these repeats are in general highly variable, but one region in the polyubiquitin is extremely homogeneous, with seven repeats absolutely identical. Such extended stretches of homogeneity have never been observed in ubiquitin genes and since substitutions are common in other coding units, it is likely that these repeats are the product of a very recent homogenization or amplification.
J Mol Evol 1995 Nov
PMID:Concerted evolution in protists: recent homogenization of a polyubiquitin gene in Trichomonas vaginalis. 749 Jul 69

Ubiquitin gene expression and the ubiquitination of proteins in the posterior silk glands (PSG) of B. mori were analyzed developmentally with respect to fibroin synthesis and degeneration. Two ubiquitin transcripts are expressed throughout larval stages, and the level of each transcript is regulated differently. The larger transcript, a polyubiquitin mRNA, was abundant during the molt stage, while levels of the smaller ubiquitin transcript increased immediately after molting. Only a single 65 kDa ubiquitinated protein was detected late in the 5th instar, and the amount increased up to spinning stage. This ubiquitinated protein may participate in the PSG degeneration.
Insect Biochem Mol Biol 1994 Jul
PMID:Protein ubiquitination in the posterior silk glands of Bombyx mori. 752 Aug 1

Ubiquitin cross-reactive protein (UCRP), a 15-kDa interferon-induced protein, is a sequence homolog of ubiquitin that is covalently ligated to intracellular proteins in a parallel enzymatic reaction and is found at low levels within cultured cell lines and human tissues not exposed to interferon. Ubiquitin and UCRP ligation reactions apparently target distinct subsets of intracellular proteins, as judged from differences in the distributions of the respective adducts revealed on immunoblots. In this study, successive passages of the human lung carcinoma line A549 in the presence of neutralizing antibodies against alpha and beta interferons had no effect on the levels of either free or conjugated UCRP, indicating that these UCRP pools are constitutively present within uninduced cells and are thus not a consequence of autoinduction by low levels of secreted alpha/beta interferon. In an effort to identify potential targets for UCRP conjugation, the immunocytochemical distribution of UCRP was examined by using affinity-purified polyclonal antibodies against recombinant polypeptide. UCRP distributes in a punctate cytoskeletal pattern that is resistant to extraction by nonionic detergents (e.g., Triton X-100) in both uninduced and interferon-treated A549 cells. The cytoskeletal pattern colocalizes with the intermediate filament network of epithelial and mesothelial cell lines. Immunoblots of parallel Triton X-100-insoluble cell extracts suggest that the cytoskeletal association largely results from the noncovalent association of UCRP conjugates with the intermediate filaments rather than direct ligation of the polypeptide to structural components of the filaments. A significant increase in the sequestration of UCRP adducts on intermediate filaments accompanies interferon induction. These results suggest that UCRP may serve as a trans-acting binding factor directing the association of ligated target proteins to intermediate filaments.
Mol Cell Biol 1994 Dec
PMID:Conjugates of ubiquitin cross-reactive protein distribute in a cytoskeletal pattern. 752 57

Ubiquitin-conjugating (E2) enzymes contain several regions within their catalytic domains that are highly conserved. However, within some of these conserved regions are several residues that may be used to define different classes of catalytic domains for the E2 enzymes. One class can be defined by the Ubc1 protein, which contains K-65, D-90, and D-120, while the corresponding positions within the Cdc34 (Ubc3) protein, which defines a second class of enzymes, contain S-73, S-97, and S-139, respectively. The presence of these differences within otherwise highly conserved regions of this family suggests that these residues may be critical for the specificity of Cdc34 function or regulation. Therefore, we have constructed a series of cdc34 alleles encoding mutant proteins in which these serine residues have been changed to other amino acid residues, including alanine and aspartic acid. In vivo complementation studies showed that S-97, which lies near the active site C-95, is essential for Cdc34 function. The addition of a second mutation in CDC34, which now encoded both the S97D and S73K changes, restored partial function to the Cdc34 enzyme. Moreover, the deletion of residues 103 to 114 within Cdc34, which are not present in the Ubc1-like E2s, allowed the S73K/S97D mutant to function as efficiently as wild-type Cdc34 protein. Finally, the cloning and sequencing of the temperature-sensitive alleles of CDC34 indicated that A-62 is also unique to the Cdc34 class of E2 enzymes and that mutations at this position can be detrimental to Cdc34 function. Our results suggest that several key residues within conserved regions of the E2 enzyme family genetically interact with each other and define a class of E2 catalytic domains.
Mol Cell Biol 1995 Oct
PMID:Intragenic suppression among CDC34 (UBC3) mutations defines a class of ubiquitin-conjugating catalytic domains. 756 15


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