Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The work described in this paper was done to see whether the partial suppression of temperature-sensitive aminoacyl-tRNA synthetase mutations by ribosomal mutations is restricted to the aminoacyl-tRNA synthetase mutation which was used for the selection of the suppressor strains or whether the ribosomal mutations can also suppress mutations of other aminoacyl-tRNA synthetases. It is shown that a mutation in ribosomal protein S5 which was selected for suppression of an alanyl-tRNA synthetase mutation (alaS-3) can also partially compensate the temperature-sensitivity of two valyl-tRNA synthetase mutants and of another alanyl-tRNA synthetase mutant. Furthermore, revertants of a temperature-sensitive valyl-tRNA synthetase mutant were isolated and screened for alterations in ribosomal proteins by electrophoretic and immunochemical methods. Alterations in at least two proteins, S8 and S20, were clearly observed among the mutants. The alteration in protein S8 renders the growth of this strain severely cold-sensitive. Presence of the mutation in protein S8 is strictly correlated with suppression of temperature-sensitivity. The S8 mutation maps between strA and spc on the Escherichia coli chromosome. Five suppressor strains have quantitatively or qualitatively altered ribosomal proteins S20. In one strain no S20 protein could be detected at all, employing different electrophoretic and immunological methods. All five suppressor mutations map in the thr-leu region of the E. coli chromosome, i.e. in an area where the alteration of protein S20 in two alaS suppressor strains has been localized previously.
Mol Gen Genet 1975 Dec 09
PMID:Alteration of ribosomal proteins in revertants of a valyl-tRNA synthetase mutant of Escherichia coli. 76 30

Reversible change of 50 S ribosomal subunits to 40 S particles takes place in cold buffered 0.5 M NH4Cl solutions either containing Mg++ (up to 0.1 M), or free from Mg++ and even supplemented with EDTA (1 mM). The 40 S particles were stable only within a definite temperature range. Heating of the samples caused completely irreversible unfolding of the 40 S particles. This "melting" appeared to be co-operative and took place within a very narrow range of temperature, which for samples containing Mg++ was a linear function of the log of Mg++ concentration. The results suggest that two types of bonds maintained the compact structure of the ribosomal subunits: ionic bonds involving Mg++ and heat-labile weak interactions between ribosomal components.
Mol Biol Rep 1976 Sep
PMID:Loosening and unfolding of E. coli 50 S ribosomal subunits: dependence on magnesium content and temperature. 79 99

1. The elevated beta-receptor responsiveness to adrenergic stimuli makes subjects with the primary hyperkinetic cardiac syndrome ideal for studying the electrical and dynamic responses of the heart to sympathetic activation. 2. In twelve men presenting with the syndrome, the effects of mental arithmetic and painful (cold) stress on the cardiac inotropic state were tested and correlated with the concomitant electrocardiographic changes. 3. Arithmetic and cold evoked responses opposite and divergent from the base-line state: the former induced vasodilatation, enhancement of cardiac rate, output, contractility and deep T wave inversion; the latter caused vasoconstriction, cardiac depression and full restoration of repolarization. 4. The sympathetic outflow elicited by stress is not generalized, but selectively directed to different circulatory levels in relation to the stimulus at work; cardiac sympathetic stimulation or inhibition has opposite effects on the repolarization phase.
Clin Sci Mol Med Suppl 1975 Jun
PMID:Electrical and dynamic responses of the human hyperkinetic heart to sympathetic stimuli. 80 42

One- and two-dimensional gel electrophoresis was employed to characterize and compare ribosomal subunit proteins from wild-type D. melanogaster and several mutants, including suppressor-of-forked and four X-linked cold sensitive lethals. The sibling species D. simulans was also studied. We found the electropherogram patterns indistinguishable in all cases.
Mol Gen Genet 1976 Aug 19
PMID:The ribosomes of Drosophila. IV. Electrophoretic identify among ribosomal subunit proteins from wild type and mutant D. melanogaster and D. simulans. 82

Antisuppressors were screened for with the help of informational suppressors in Podospores anserina. Four mutations in the AS1 locus and two in the AS2 locus were isolated, using allele non specific suppressors supposed to be ribosomal ambiguity mutations. Four mutations in the AS3 locus and 45 in the AS4 locus were obtained, using a nonsense (t-RNA like) suppressor. All antisuppressors are partially dominant. Most mutations in the AS4 locus are lethal. The four mutants at the AS3 locus and 6 out of the 8 viable mutants at the AS4 locus are cold sensitive. Phenotypic properties and action spectra of the antisuppressors suggest that they are restrictive ribosomal mutations.
Mol Gen Genet 1976 Sep 23
PMID:Genetic evidence of ribosomal antisuppressors in Podospora anserina. 96 60

Repair synthesis of DNA per se at pachytene is not needed for commitment to meiotic recombination although it is a necessary event to follow. Recombination frequency is governed by the rate of nicking and the time in which unrepaired nicks are allowed to match and crossover. Cold treatment at pachytene prevented repair synthesis, hence open nicks were accumulated to match and crossover, and a 3-fold increase in recombination resulted. The kinetics of cold temperature effect followed a quadratic function as shown by a computer simulation which agreed with our experimental data (Lu, 1974b). High temperature did not change the rate of repair synthesis. It did cause an increased nicking which led to a twofold increase in recombination and which entailed a higher rate of recovery repair synthesis.
Mol Gen Genet 1976 Aug 19
PMID:Genetic recombination of Coprinus. V. Repair synthesis of deoxyribonucleic acid and its relation to meiotic recombination. 98 25

1. Dogs cooled to 27 degrees C were compared with control dogs maintained at 38 degrees C. The mean arterial blood pressure, renal blood flow and glomerular filtration rate were lower in the hypothermic animals. 2. The relation between mean arterial blood pressure and renal blood flow was investigated. Auto-regulation of renal blood flow occurred in the kidneys of normothermic and hypothermic animals. Thus the reduction in renal blood flow during hypothermia is not due simply to the fall in mean arterial blood pressure. 3. Similarities between recordings of renal blood flow obtained at 38 degrees C and 27 degrees C suggest that its autoregulation occurs by the same mechanism at the two temperatures. 4. Autoregulation of renal blood flow occurred in hypothermic kidneys in the presence of a cold-induced vasoconstriction. The observed responses to cold and to alterations in mean arterial blood pressure may take place in different areas of the renal vasculature.
Clin Sci Mol Med Suppl 1975 Jun
PMID:Autoregulation of renal blood flow in dogs at normal body temperature and at 27 degrees C. 105 80

Two chloramphenicol resistance mutations out of 123 tested in Aspergillus nidulans are inherited extranuclearly as judged by transmissibility in heterokaryons, lack of segregation at meiosis, and independent segregation from all of the eight nuclear linkage groups. They do not recombine with each other. However, experiments in collaboration with G. Turner and R.T. Rowlands show that they do recombine with cytoplasmic mutations to oligomycin resistance (Rowlands and Turner, 1973) and cold-sensitivity (Waldron and Roberts, 1973). These cytoplasmic chloramphenicol resistance mutations are stable and do not affect growth or morphology on antibiotic-free media. Nuclear mutations to chloramphenicol resistance map at a minimum of three loci. At one of these loci, most, but not all, mutations lead pleiotropically to cycloheximide hypersensitivity, and most of these, but not all, also confer pleiotropic hypersensitivity to salicylhydroxamic acid.
Mol Gen Genet 1975
PMID:Cytoplasmic and nuclear mutations to chloramphenicol resistance in Aspergillus nidulans. 110 19

A mutant has been isolated which carries a nuclear mutation capable of suppressing certain aspects of the phenotype imposed by a specific mitochondrial mutation. The mitochondrial mutation [tso-r] confers cold sensitivity to growth on nonfermentable substrates and resistance to oligomycin. When both the mitochondrial and nuclear mutations are present in the same cell the cell is phenotypically cold resistant but retains a high level of oligomycin resistance. The extent of cold sensitivity suppression is dependent upon other unspecified nuclear genes. The molecular basis for the suppression may involve interactions between cytoplasmic and mitochondrial ATPase.
Mol Gen Genet 1975 Oct 22
PMID:Biogenesis of mitochondria 40. Phenotypic suppression of a mitochondrial mutation by a nuclear gene in Saccharomyces cerevisiae. 110 3

Six cold-sensitive variants have been isolated from Chinese hamster ovary cells by the BUdR-visible light selection technique. The properties of one of these lines have been studied in detail. This line stops dividing immediately after a shift from 39 degrees C to 33 degrees C though its doubling time at 39 degrees C is only slightly longer than that of wild-type cells. The rates of DNA and protein synthesis are severely reduced at 33 degrees C, but the rate of RNA synthesis is not significantly different from wild-type cells. This line may be defective in protein synthesis, but the results of sedimentation analysis indicate that it probably has normal ribosomal subunit assembly.
Mol Gen Genet 1975 Jun 19
PMID:Isolation of cold-sensitive Chinese hamster cells. 123 84


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