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

Comparison of growth rates of isogenic strains that synthesize varying levels of beta-galactosidase during continuous culture on non-inducing medium indicates that synthesis of low levels of non-functional protein has a small but possibly significant effect upon growth rate.
J Mol Evol 1976 Dec 30
PMID:Selective disadvantage of non-functional protein synthesis in Escherichia coli. 79 67

The multiplicity of the genes for ribosomal RNA varies in several ways. The series of bb mutants are an example of mutant phenotypes associated with deficiencies of the rDNA. In certain genotypes the amount of rDNA present can disproportionately replicate and in some cases become incorporated into the chromosome and thus inherited. In other cases there is no stabilization of the increased multiplicity of rRna genes. In still other cases the multiplicity of rDNA does not change. We describe cases of increased, but non-functional, multiplicity of rDNA in compound chromosomes routinely used in analyses of these phenomena and discuss the associated problems.
Mol Gen Genet 1975 Aug 05
PMID:Disproportionately-replicated, nonfunctional rDNA in compound chromosomes of Drosophila melanogaster. 80 61

Gene targeting of a chromosomally integrated transgene in Arabidopsis thaliana is reported. A chimeric gene consisting of the promoter of the 35S RNA of CaMV, the polyadenylation signal of the octopine synthase gene and the coding region of the bacterial hygromycin phosphotransferase gene (hpt), which was rendered non-functional by deletion of 19 bp, was introduced into the genome of A. thaliana using Agrobacterium-mediated gene transfer. A total of 3.46 x 10(8) protoplasts isolated from 17 independent transgenic Arabidopsis lines harbouring the defective chimeric hpt gene were transformed via direct gene transfer using various DNA forms containing only the intact coding region of the hpt gene. Out of 150 hygromycin-resistant colonies appearing in the course of these experiments, four were the result of targeted recombination of the incoming DNA with the defective chromosomal locus as revealed by PCR and Southern blot analysis. Comparison with the number of transformants obtained when an hpt gene controlled by a promoter and terminator from the nopaline synthase gene was employed results in a maximal ratio of homologous to non-homologous transformation in A. thaliana of 1 x 10(-4).
Mol Gen Genet 1992 Jan
PMID:Gene targeting in Arabidopsis thaliana. 131 May 19

To further evaluate whether transsynaptic mechanisms account for stress-induced changes in adrenomedullary preproenkephalin mRNA (ppEnk mRNA), neonatal rats were made hypoglycemic at a time when synapses are non-functional (less than 10 days postnatal age). While ppEnk mRNA in medullae from adult rats increased as much as 60-fold in this paradigm (insulin 10 U/kg), ppEnk mRNA levels in the newborn increased only 1.6-fold (insulin 20 U/kg). To evaluate whether postsynaptic cholinergic pathways of the neonatal adrenal medulla were functional, we treated 5-day-old pups with cholinergic agonists (nicotine [1 mg/kg, s.c., q 12 h] + carbachol [1.7 mumol/kg, s.c., q 12 h x 4 days]). Combined cholinergic agonist treatment augmented enkephalin prohormone and peptide levels up to 3-fold (P less than 0.05). To determine whether the blunted response to hypoglycemia in the newborn resulted from a deficiency in functional transsynaptic activity, synapses were matured using thyroid hormone pretreatment (postnatal days 2 and 3) before hypoglycemic stress. Hypoglycemia now caused a 40-fold increase in adrenomedullary ppEnk mRNA levels only in the T3/insulin treated group. To exclude other secondary effects of hypoglycemia (eg. hormonal, or insulin treatment-dependent), intracellular glycopenia was produced in the presence of secondary hyperglycemia by injecting adult rats or pups with 2-deoxyglucose (500 mg/kg). Similar to the insulin-hypoglycemia group, a large increase in adrenomedullary ppEnk mRNA resulted in the adult but not in the 5-day-old neonatal adrenal medullae. We conclude that enkephalin biosynthesis, like co-stored catecholamines, is induced by a transsynaptic process.(ABSTRACT TRUNCATED AT 250 WORDS)
Brain Res Mol Brain Res 1992 Apr
PMID:Regulation of adrenomedullary preproenkephalin mRNA: effects of hypoglycemia during development. 131 92

pTB19, a 27 kb plasmid originating from a thermophilic Bacillus species, contains integrated copies of two rolling-circle type plasmids on a 10.6 kb DNA fragment. In the present study we analysed the part of pTB19 that contains the rolling-circle plasmid pTB913 and the region in between the two rolling-circle plasmids. We show that, in the integrated state, pTB913 was flanked by a 55 bp direct repeat that duplicated part of the replication initiation gene repB. Since repB was interrupted, the integrated pTB913 could not initiate rolling-circle replication. Autonomously replicating pTB913 was produced from pTB19, probably through recombination between the 55 bp direct repeats; this was a rare event. Since the second integrated rolling-circle type plasmid also contained a non-functional replication initiation gene, replication of pTB19 must be controlled by the RepA determinant. Theta-type replication, controlled by RepA is likely to account for the high stability of pTB19. In between the two integrated rolling-circle plasmids was present an open reading frame (447 codons) which could encode a protein of unknown function.
Mol Gen Genet 1992 Jun
PMID:The integrated state of the rolling-circle plasmid pTB913 in the composite Bacillus plasmid pTB19. 132 Jan 90

Several cDNA clones encoding a 21.7-kDa antigen (Sm21.7) were detected from a Schistosoma mansoni sporocyst cDNA expression library using irradiated cercaria-vaccinated rabbit serum. The antigen was designated 'vaccine dominant' because parasite-derived Sm21.7 was recognised preferentially by mouse vaccine sera compared with mouse infection sera. The cDNA and corresponding gDNA sequences showed 64% identity at the nucleotide level and 47% identity at the amino acid level with the sequence of a previously described S. mansoni tegumental antigen, sma22.6. Whereas sma22.6 mRNA occurs almost exclusively in the adult worm, Sm21.7 mRNA was equally abundant in the sporocyst, schistosomular and adult stages. Both Sm21.7 and sma22.6 sequences reveal a motif strongly homologous to the EF hand calcium binding domain but lacking the invariant glycine in the calcium binding loop. The disruptive nature of the glutamine which in Sm21.7 replaces the glycine explains why the motif is non-functional, as shown by the inability of Sm21.7 to bind calcium.
Mol Biochem Parasitol 1992 Feb
PMID:Cloning of a 21.7-kDa vaccine-dominant antigen gene of Schistosoma mansoni reveals an EF hand-like motif. 137 27

Molecular hybridisation using a ricin cDNA probe has revealed that the ricin/Ricinus communis agglutinin (RCA) multigene family is composed of approximately eight members. Several genomic clones containing preproricin and preproricin-like sequences have been isolated. Partial analysis of three different genomic clones by DNA sequencing and ribonuclease protection has indicated that at least three members of the lectin gene family are non-functional. None of the original seventeen positive clones isolated appears to contain a Ricinus communis agglutinin (RCA) gene. One gene member analysed (pCBG3H1) represents a functional ricin gene similar in coding sequence to the published cDNA sequence and possesses typical eukaryotic consensus sequences and seed-specific elements within the flanking sequences. Investigation at the transcriptional level of the expression pattern of this gene revealed that mRNA accumulates during the post-testa stages of seed development. The pattern of accumulation of steady-state transcripts correlates closely with that previously observed at the protein and translatable RNA levels.
Plant Mol Biol 1992 Feb
PMID:The lectin gene family of Ricinus communis: cloning of a functional ricin gene and three lectin pseudogenes. 137 5

Guanethidine sulphate causes destruction of peripheral sympathetic neurons and infiltration of mononuclear inflammatory cells in the sympathetic ganglia of both athymic nude (rnu/rnu) and euthymic LEW/Mol rats. The effect of guanethidine is believed to be an autoimmune reaction. To determine the effect of immunosuppressive drugs concurrently with guanethidine treatment both athymic and euthymic rats were treated with guanethidine 40 mg/kg i.p. daily for 14 days, cyclophosphamide 100 mg/kg i.p. on days 1 and 8, methylprednisolone 10 mg/kg and cyclosporin A 10 mg/kg daily from days 1 to 7, and then every other day from days 8 to 14. The number of neurons in the sympathetic ganglia was counted and four subpopulations of mononuclear inflammatory cells were identified by monoclonal antibodies MHC II, CD8 T-cells/NK-cells, CD5 T-cells, CD4 T-cells/macrophages. Our results show that the immunosuppressive drugs used were unable to prevent the guanethidine-induced reduction of sympathetic neurons, although the number, of neurons following guanethidine-methylprednisolone treatment was significantly higher compared with guanethidine alone in both athymic and euthymic rats. The identification of mononuclear cells in the sympathetic ganglia showed that the CD8/NK and CD5 populations were the populations primarily responding to guanethidine treatment. Both CD8/NK and CD5 populations were absent without guanethidine, but increased significantly following guanethidine in both athymic and euthymic animals. None of the immunosuppressive drugs used could prevent the guanethidine-induced rise in the CD8/NK population in neither athymic nor in euthymic rats. The rise in the CD5 population was suppressed following treatment with all immunosuppressive drugs in athymic rats, but only following methylprednisolone in euthymic animals. These results indicate that guanethidine induces proliferation of T-cells in euthymic rats and non-functional CD5 positive pre T-cells in athymic animals. The CD5 population in both athymic and euthymic animals appears relatively more sensitive to immunosuppressive drugs than the NK-cell population also activated by guanethidine. This relatively resistant NK-cell population seems to play an important role in the guanethidine-induced destruction of sympathetic neurons and can explain why the guanethidine-induced immunological reaction could not be fully prevented by the immunosuppressive drugs used. The conclusion is that guanethidine induces destruction of sympathetic neurons by a NK-cell-mediated reaction.
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PMID:Effect of immunosuppressive agents on the guanethidine-induced sympathectomy in athymic and euthymic rats. 138 39

The ribosomal frameshift signal in the genomic RNA of the coronavirus IBV is composed of two elements, a heptanucleotide "slippery-sequence" and a downstream RNA pseudoknot. We have investigated the kinds of slippery sequence that can function at the IBV frameshift site by analysing the frameshifting properties of a series of slippery-sequence mutants. We firstly confirmed that the site of frameshifting in IBV was at the heptanucleotide stretch UUUAAAC, and then used our knowledge of the pseudoknot structure and a suitable reporter gene to prepare an expression construct that allowed both the magnitude and direction of ribosomal frameshifting to be determined for candidate slippery sequences. Our results show that in almost all of the sequences tested, frameshifting is strictly into the -1 reading frame. Monotonous runs of nucleotides, however, gave detectable levels of a -2/+1 frameshift product, and U stretches in particular gave significant levels (2% to 21%). Preliminary evidence suggests that the RNA pseudoknot may play a role in influencing frameshift direction. The spectrum of slip-sequences tested in this analysis included all those known or suspected to be utilized in vivo. Our results indicate that triplets of A, C, G and U are functional when decoded in the ribosomal P-site following slippage (XXXYYYN) although C triplets were the least effective. In the A-site (XXYYYYN), triplets of C and G were non-functional. The identity of the nucleotide at position 7 of the slippery sequence (XXXYYYN) was found to be a critical determinant of frameshift efficiency and we show that a hierarchy of frameshifting exists for A-site codons. These observations lead us to suggest that ribosomal frameshifting at a particular site is determined, at least in part, by the strength of the interaction of normal cellular tRNAs with the A-site codon and does not necessarily involve specialized "shifty" tRNAs.
J Mol Biol 1992 Sep 20
PMID:Mutational analysis of the "slippery-sequence" component of a coronavirus ribosomal frameshifting signal. 140 64

The interaction between homologous DNA sequences, distant from each other in the chromosome, was examined in the cyanobacterium Synechocystis PCC 6803. Most of the rbcL gene encoding the large subunit of ribulose bisphosphate carboxylase/oxygenase (Rubisco) was duplicated in the genome by a targeted insertion of a 3'-truncated gene copy into the psb A-I locus. Both rbcL genes, in the psb A-I region and at the rbc locus, were non-functional; The former due to the 3' truncation, and the latter due to a deletion in the 5'-region (creating a 5' truncation) and a mutation associated with an insertion of the Rhodospirillum rubrum rbc gene, yielding a high-CO2-requiring mutant ('cyanorubrum'). The 3' and the 5' truncated rbcL genes were linked to chloramphenicol and kanamycin resistance markers, respectively. Decreasing the kanamycin selective pressure concomitantly with exposure of the double resistance mutant to air, resulted in air-growing colonies. Analysis of their genomes, Rubisco proteins, and their ultrastructure revealed: 1) Reconstitution of a full-length cyanobacterial rbcL gene at the rbc locus; 2) simultaneous synthesis of the cyanobacterial (L8S8) and R. rubrum (L2) enzymes in meroploids containing both mutated and reconstituted rbcL genes; 3) reappearance of carboxysomes. Our results indicate extensive recombinatorial interactions between the homologous sequences at both loci leading to reconstitution of the cyanobacterial rbcL gene.
Mol Gen Genet 1992 Nov
PMID:Restoration of the wild-type locus in an RuBP carboxylase/oxygenase mutant of Synechocystis PCC 6803 via targeted gene recombination. 146 99


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