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

Plasmid and phage deoxyribonucleic acid (DNA) harboring bacterial insertion sequence (IS) elements IS1, IS2, and IS5 were characterized and used as probes to detect homologous sequences in various procaryotic and eucaryotic genomes. The hybridization method used permits the detection of sequences partially homologous to the elements. Hybridization of the IS-containing probes to each other revealed a region of limited homology between IS1 and IS2. Homologous sequences were then detected by computer analysis of the published IS1 and IS2 nucleotide sequences. The homologous sequence contains a tandemly repeated tetranucleotide sequence which resembles the repeated sequence at the hot spot for spontaneous mutations in the lacI gene (P. J. Farabaugh, U. Schmeissner, M. Hofer, and J. Miller, J. Mol. Biol. 126:847-863, 1978). Homology between the IS elements and various genomes was determined by hybridizing labeled DNA containing IS1, IS2, and IS5 sequences to Southern blots of chromosomal DNA cleaved with restriction endonucleases. IS1 and IS5 appear limited to the enteric bacteria, whereas IS2 sequences can also be detected in Pseudomonas putida, Pseudomonas aeruginosa, and Serratia marcescens. Bacteria which appear not to possess extrachromosomal elements, e.g., Caulobacter crescentus, did not show homology with any insertion sequences tested. In addition, sequences homologous to IS1, IS2, or IS5 were not detected in Saccharomyces cerevisiae, Dictyostelium discoideum, or calf thymus DNA.
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PMID:Deoxyribonucleic acid sequence homologies among bacterial insertion sequence elements and genomes of various organisms. 15 91

Using a mathematical model of carbohydrate metabolism in Dictyostelium discoideum, the kinetic expressions describing the activities of glucokinase and glucose-6-P phosphatase have been analyzed. The constraints on the kinetic mechanisms and relative activities of these two enzymes were investigated by comparing computer simulations to experimental data. The results indicated that, (1) glucose-6-P is compartmentalized with respect to the enzymes involved in glucose-60P, trehalose and glycogen metabolism, (2) a differences of approximately 0.6 mM/min in maximum specific activity of glucokinase compared to glucose-6-P phosphatase is required in order for the model to produce end product carbohydrate levels consistent with those observed experimentally, (3) the Km of glucokinase for glucose strongly influences the steady state levels of glucose in the absence of external glucose, and (4) changing the order of product removal in the reaction catalyzed by glucose-6-P phosphatase influences the level of glycogen and trehalose.
Mol Cell Biochem 1978 Apr 11
PMID:A kinetic analysis of glucokinase and glucose-6-P phosphatase in Dictyostelium. 20 18

Crude membranes from vegetative and aggregation competent cells of Dictyostelium discoideum Ax 2 were separated by a combination of differential and sucrose gradient centrifugation. A fraction mainly containing plasma membranes could be isolated. The high degree of purity was demonstrated by electron microscopy and by the presence of marker enzymes typical for the plasma membrane and the absence of enzymes characteristic for other subcellular compartments. Furthermore surface labelling with radioactive 1--fluoro--2,4--dinitrobenzene--14C and cAMP binding capacity were introduced as plasma membrane markers. In the pure plasma membrane fraction endogenous activities of D--mannosyl-, D--glucosyl- and N--Acetyl--D--glucosaminyl--transferases were present. The activities in plasma membranes of aggregation competent cells were up to thirty times higher than in membranes isolated from vegetative cells.
Mol Cell Biochem 1978 Jun 28
PMID:Localization of glycosyl transferases in plasma membranes from Dictyostelium discoideum. 20 11

Complementation tests were performed on 10 strains of Dictyostelium discoideum which carry developmental mutations representing aggregation loci identified previously in two independent studies. When the 5 aggregation-deficient strains representing loci CGI-5 were fused with the 5 strains carrying mutations at loci ago A-E, all 25 crosses produced aggregation-competent diploids. Complicating factors, such as negative gene interactions and possible interallelic complementation are discussed. The results of this experiment suggest that the 10 aggregation loci identified in the two studies are different and that aggregation loci in D. discoideum are probably not associated with significant mutational "hot-spots".
Mol Gen Genet 1977 Mar 16
PMID:Evidence against mutational "hot-spots" at aggregation loci in Dictyostelium discoideum. 55 42

Simple parasexual genetic techniques have been employed to extend the linkage analysis initiated in an earlier study (Coukell, 1975) of developmental mutations (agg mutations) in 40 independently isolated aggregation-deficient mutants of Dictyostelium discoideum. Using these techniques, agg mutations in 28 of the 40 mutants have been assigned to 4 linkage groups: 16 in group II, 1 in group III, 10 in group IV, and 1 in group VI. None of the agg mutations analyzed appear to map in linkage group I. In addition, a new temperature-sensitive growth locus, designated tsgJ, was mapped in group III. It was also found that diploid strains of D. discoideum are readily induced to undergo haploidization when grown on 0.1% p-fluorophenylalanine (PFP) at 25.5 degrees C. Growth of diploid strains on PFP had no effect on the type of segregant classes obtained (i.e. PFP does not induce mitotic crossing-over), the subsequent growth and/or development of the segregants, or the ability of the segregants to reform stable diploids.
Mol Gen Genet 1977 Mar 16
PMID:Linkage analysis of developmental mutations in aggregation-deficient mutants of Dictyostelium discoideum. 55 43

In the slime mold Dictyostelium discoideum polysioprenylphosphomannosides are substrates for membrane bound mannosyltransferases; the isolated and purified isoprenyl derivatives transfer mannose to protein in vitro in presence of membrane fractions. The biosynthesis of the mannolipids as well as the biosynthesis of a glucose containing cerebroside, which becomes synthesized in an early stage of the cell development proceeds under control of the cell differentiation. The isolation procedure and the properties of the glycolipids are described, and their functions for the cellular development are discussed.
Mol Cell Biochem 1978 Jun 15
PMID:The biosynthesis of glycolipids during the differentiation of the slime mold Dictyostelium discoideum. 56 48

Antibodies, shown to be specific for DNA/RNA hybrids, have been covalently attached to CNBr-activated Sepharose. The resultant affinity resin specifically binds DNA/RNA hybrids and has been used to enrich for the DNA which codes for rRNA in the slime mold Dictyostelium discoideum. By utilizing the technique of R-loop formation, DNA molecules containing the rRNA genes were isolated from total nuclear DNA in a double-stranded form. These rDNA molecules, which were recovered by high salt elution from the affinity resin, were typically 15-40 kbp in length, and thus contained DNA sequences adjacent to the selected sequences coding for the 17S and 26S rRNAs. In addition, evidence has been obtained concerning the structure of Dictyostelium rDNA which agrees with the finding (Taylor et al. (1977) ICN-UCLA Symp. Mol. Cell. Biol. 8, 309-313) that the rDNA molecules are not covalently attached to the chromosomes of this organism.
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PMID:Gene enrichment using antibodies to DNA/RNA hybrids: purification and mapping of Dictyostelium discoideum rDNA. 72 37

Some aspects of DNA repair in several radiation-resistant and radiation-sensitive strains of Dictyostelium discoideum were investigated by using alkaline sucrose gradients to analyze for the production and resealing of single-strand breaks following irradiation with 254 nm UV. All radiation-resistant strains and all mutants assayed that are sensitive to both UV and 60Co gamma rays produced single-strand breaks in their nuclear DNA after a UV fluence of 15 M/m2. Mutants at the radC locus which are sensitive to UV but as resistant as their parental strains to 60Co gamma rays produced many fewer single-strand breaks in their DNA after irradiation with UV. Thus, the radC mutations alter a repair pathway specific for UV-induced DNA damage and presumably affect the activity of a UV-damage-specific endonuclease involved in excision repair. All radiation-resistant strains and all of our mutants sensitive to gamma rays rejoined much of their DNA during a three-hour post-UV-irradiation incubation, suggesting that these strains have at least a partially intact excision repair system.
Mol Gen Genet 1979 Jan 02
PMID:In vivo nicking and rejoining of nuclear DNA in ultraviolet-irradiated radiation-resistant and sensitive strains of Dictyostelium discoideum. 76 36

Haploid strains of Dictyostelium discoideum carrying radiation-sensitive mutations in both the radA and radC genes are more sensitive to UV light irradiation than the "additive" sensitivity of the single-mutant haploids. This synergistic interaction indicates that the radA and radC gene products are involved in two different pathways of repair following UV-induced DNA damage. Double-mutant haploids bearing mutations in both the radA and radB genes have the same sensitivity as the radB single mutant indicating that the radA and radB gene products are involved in the same repair pathway.
Mol Gen Genet 1979 Jan 02
PMID:Interactions between radiation-sensitive mutations in double-mutant haploids of Dictyostelium discoideum. 76 37

A cell aggregate of Dictyostelium discoideum either constructs a fruiting body directly or transforms into a migrating slug and fruits later on in some other locale. In the presence of formycin B, an inosine analog, and in an environment that otherwise favors fruiting, aggregates having reached a relatively late (17 hr) stage of fruit construction abandon that program and transform into migrating slugs. They then revert to the fruiting mode and construct normal fruiting bodies without further interference [Brackenbury et al. (1974) J. Mol. Biol. 90, 529-539]. The data presented here suggest that formycin B exerts its morphogenetic effect by interfering competitively with the metabolism of guanosine. Thus: see article. The recovery from formycin B is thought to result from the ensuing accumulation of guanosine and reversal of the inhibition. In support of this are the following: (1) Formycin B does cause, in vivo, an accumulation of guanosine. Exogenoug guanosine reverses the effect of formycin B, depending on their relative concentrations. (2) Guanosine is phosphorylitically cleaved to guanine and ribose-1-P by purine ribonucleoside phosphorylase (purine-nucleoside:orthophosphate ribosyl transferase, EC 2.4.2.1), present in D. discoideum extracts, and formycin B is a competitive inhibitor or this reaction with a very high affinity for the enzyme. (3) Four other analogs, also competitive inhibitors of this enzyme, produce precisely the same morphogenetic deviation. The concentrations required are consistent with the relative K1 values.
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PMID:Guanosine metabolism and regulation of fruiting body construction in dictyostelium discoideum. 81 95


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