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)

From a collection of 8,000 transposon-insertion mutants of Escherichia coli K12 we identified two mutations, trg-1::Tn5 and trg-2::Tn10, that simultaneously eliminate chemotactic response to ribose and galactose, two attractants recognized by independent receptors. We show that these transposon-insertions confer a Trg phenotype, indicating that this specific pattern of tactic defects is a null phenotype. The two mutation sites are cotransductionally linked to an extend consistent with placement in the same gene. The Trg phenotype of a family of deletion mutants produced by curing trg-2::Tn10 implies that trg is a single gene. Experiments with appropriate F-primes and Hfr's locate the trg locus at approximately 31 min on the linkage map, with a marker order: pyrF-rac-(P.O. 43)-trg-man. We also found one trg mutant whose Trg phenotype was not linked to a transposon-insertion but is probably the result of a mutator activity in the parent strain. Selection of transposon-insertions near, but not in trg allowed demonstration of a very close linkage between the spontaneous trg-3 and the transposon-generated trg's, indicating all three mutations are probably in the same gene. In our manipulations of transposon-insertions we found that Tn5 had a tendency to translocate from its initial site of insertion while Tn10 was relatively stable. The trg-product is probably a chemotactic signal transducer, which interacts directly with two independent receptor proteins and transmits information to the central chemotactic machinery.
Mol Gen Genet 1979 Mar 20
PMID:Transposon-insertion mutants of Escherichia coli K12 defective in a component common to galactose and ribose chemotaxis. 37 29

Studies were undertaken to determine if mitochondrial rRNA synthesis in yeast is regulated by general cellular stringent control mechanism. Those variables affecting the relaxation of a cycloheximide-induced stringent response as a result of medium-shift-down or tyrosine limitation include: 1) the stage of cell growth, 2) carbon source, 3) strain differences and, 4) integrity of the cell wall. The extent of phenotypic relaxation decreased or was eliminated entirely in a strain dependent manner as cells entered stationary phase of growth or by growth of cells on galactose or in osmotically stabilized spheroplast cultures. Cytoplasmic and mitochondrial RNA species were extracted from regrowing spheroplast cultures subjected to different experimental regimens and analyzed by electrophoresis on 2.5% polyacrylamide gels. Relative rates of synthesis were determined in pulse experiments and normalized by double-label procedures to longterm label material. Tyrosine starvation was found to inhibit synthesis of the large and small rRNA species of both cytoplasmic and mitochondrial rRNAs to about 5-20% of the control values. Chloramphenicol inhibits mitochondrial and cytoplasmic rRNA synthesis to 60-80% of control; however, chloramphenicol addition does not relax the stringent inhibition of either class of rRNAs. Cycloheximide addition results in 70-80% inhibition of synthesis of both cellular speceis of rRNAs. As noted above, cycloheximide does not relax the stringent response of cytoplasmic rRNA synthesis in spheroplasts, and also does not relax the stringent inhibition of mitochondrial rRNA synthesis. From these studies, we conclude that both cytoplasmic and mitochondrial rRNA synthesis share common control mechanisms related to regulation of protein synthesis by shift-down or amino acid limitation.
Mol Gen Genet 1979 Jun 20
PMID:Regulation of mitochondrial ribosomal RNA synthesis in yeast. I. In search of a relaxation of stringency. 38 47

The visco-elastic properties of salivary secretions are due to high molecular-weight glycoproteins, known as mucins. Mucins are composed of numerous oligosaccharide side-chains O-glycosidically linked through 2-acetamido-2-deoxy-alpha-D-galactose to the hydroxyl groups of seryl and threonyl residues of the protein core; on the average, every fourth amino acid residue is involved in such a bond. This work conveys their isolation and purification, compiles the compositional analysis of several mammalian submaxillary and sublingual mucins; defines the conditions of the alkaline beta-elimination reaction, its mechanism, and importance in structural studies of glycoprotens, and briefly discusses the influence of stimuli on mucous secretions, as well as biosynthesis, structural diversity, and physiological role of salivary mucous glycoproteins.
Mol Cell Biochem 1979 Jan 15
PMID:Current concepts of the structure and nature of mammalian salivary mucous glycoproteins. 42 92

The subcellular localization and characterization of some of the components involved in the glycosylation of asparagine type glycoproteins was attempted using dolichyl diphosphate [14C]mannose oligosaccharide as precursor of the glycosylation reaction in vitro. Isolated rough and smooth microsomal fractions were able to carry out the transfer of the carbohydrate moiety from lipid oligosaccharide to endogenous protein acceptors. The protein glycosylating activity remained practically the same after stripping the vesicles from their robosomes or partially releasing their vesicular content. Isolation of polysomes from rough microsomes after glycosylation has taken place, reveals that a large proportion of mannose labeled glycoproteins is in the membranous fraction. The remaining labeled glycoproteins co-sediment with the polysomal fraction. If the isolation is carried out before glycosylation only the membranous fraction shows enzyme activity, whereas the polysomes alone are not able to carry out glycosylation. All these results taken together indicate that the protein glycosylating enzyme is a structural component of the rough and smooth microsomes of rat liver.
Mol Cell Biochem 1979 Jul 31
PMID:Oligosaccharide transfer from lipid sugar intermediates to endogenous protein(s) of rat liver microsomal subfractions. 50 56

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

Human liver alpha-L-fucosidase was purified to apparent homogeneity and analyzed for carbohydrate content primarily by gas-liquid chromatography (glc). The enzyme is about 7% carbohydrate by weight and contains the following sugars (residues per 50, 000 molecular weight subunit): mannose (8.3), glucosamine (4.3) (presumably N-acetylated), sialic acid (1.6) and glucose (1.6). Galactose (0.8) and L-fucose (1.8) were also found but their presence may be due to artifacts of the purification procedure.
Mol Cell Biochem 1977 Nov 25
PMID:Carbohydrate composition of purified human liver alpha-L-fucosidase. 60 Feb 69

1. Galactose utilization after intravenous injection was measured in fed and fasted man together with changes in blood glucose, lactate and insulin. 2. Feeding did not alter blood galactose half-life. 3. The mean increases in blood glucose and lactate were greater in the fasted subjects but their concentrations reached similar values in both fed and fasted states. 4. Plasma insulin increased after galactose in the fasted state, but there was no change in the fed state, indicating that galactose is not insulinogenic. 5. After an intravenous galactose load in the fed state insulin appears to inhibit hepatic glucose release. 6. An intravenous galactose test might be a useful measure of hepatic glucose release under different physiological and pathological conditions.
Clin Sci Mol Med 1978 Jan
PMID:The metabolic response to galactose as a measure of hepatic glucose release in man. 62 Apr 87

1. Hepatic carbohydrate metabolism was studied by an intravenous galactose test in control patients, malnourished non-septic patients, patients with prolonged severe sepsis and patients after recovery from sepsis. 2. Blood galactose half-life was not significantly increased in the septic group despite abnormal liver-function tests, whereas it was approximately doubled in the malnourished patients. 3. The rise in blood glucose after galactose injection was less in both the septic and malnourished groups, as compared with that in the control subjects. 4. Fasting blood glucose, lactate and pyruvate concentrations were similar in all groups, whereas blood ketone bodies were increased in the malnourished and septic groups, and blood alanine was decreased only in the septic group. 5. The changes in hepatic metabolism and function were reversible on recovery from sepsis. 6. It is suggested that alterations in hepatic blood flow and the metabolic fate of galactose within the liver may explain the changes in the metabolic response to galactose observed in malnourished or septic patients.
Clin Sci Mol Med 1978 Aug
PMID:Galactose and hepatic metabolism in malnutrition and sepsis in man. 67 28

The secondary structure of DNA is known to be largely determined by the kind of counterion bound to it. We have used the X-ray diffraction method to study the structure of magnesium and lithium salts of T2 phage DNA in oriented fibres. The structural behaviour of this glucosylated DNA in the form of magnesium and lithium salts was shown to be identical to the behaviour of the same salts of "normal" calf thymus DNA throughout the studied range of relative humidities (44-95%). However these two DNAs in the form of sodium salt are known to behave quite differently. One can presume that Mg2+ and Li+ influence the structural behaviour of double-stranded DNA so effectively as to be able to "ignore" the fact that T2 phage DNA contains glucoside residues. The results of this work and the already known facts concerning the structure of DNA in the form of various cation salts (in solution and in "solid" fibres) indicate that the structural behaviour of double-stranded DNA is mainly determined by the cation located in the region of the narrow groove of the double helix. If cations are graded according to the efficiency of their influence on the structural behaviour of DNA in fibres, the scale will coincide with that of their DNA-binding strength in water solution, that is: Mg2+ greater than Li+ greater than Na+ greater than K+ greater than Rb+. A qualitative consideration of electrostatic interaction between the cations and the negatively charged DNA strands leads one to suppose that this interaction must obstruct the transition of individual DNA molecules from the B-form to the A-form. Aggregation of self-aggregation of DNA molecules is presumed necessary to enable them to adopt the A-conformation.
Mol Biol (Mosk)
PMID:[Investigation of the structure of magnesium and lithium salts of T2 phage DNA by the method of x-ray diffraction. The possible mechanisms of the participation of cations in the structural transformation of double-stranded DNA]. 74 8

The gal3 mutation of E. coli is an insertion of a DNA sequence, 1,100 base pairs in length, into the operator-promoter region of the galactose operon. This mutation reverts spontaneously to gal+ by excision of the insertion to produce stable, inducible revertants, or by tandem duplications of the gal operon to produce unstable, constitutive revertants. The nature of a third class of revertants, which are stable and constitutive, is the subject of the present study. The stable, constitutive class of revertants included approximately 30% of all gal+ revertants obtained from a gal3 (lambda) strain. Although the constitutive reversions could be transduced by lambda, the efficiency was found to be extremely poor and the rare transductants which did appear seemed to originate from abnormal transducing particles. It was concluded that these reversions were not normally packaged by lambda. In order to facilitate the packaging of these reversions, the chlD-pgl region was deleted from the parent gal3 (lambda) strain. Unexpectedly, the gal3 mutation in the majority of these deletions reverted to produce stable, constitutive reversions exclusively. The explanation proposed was that the chlL-pgl deletions had also removed part of the gal operator-promoter. These revertants were not considered to be true representatives of the stable, constitutive class. The specificity of deletion end-points at the insertion was found only in the gal3 (lambda) strain, and not in gal+, gal+(lambda), or gal3 strains. Moreover, the frequency of spontaneous chlD-pgl deletions increased 10- to 15-fold in presence of the gal3 insertions. A lambdagal phage bearing a true stable, constitutive reversion (galc200) was isolated from the revertant strain by subsequent deletion of the chlD-pgl segment (delta31). Electron micrographs of lambdagal+ and lambdac200 delta31(chlD pgl) DNA heteroduplexes were interpreted to indicate that the stable, constitutive reversion had arisen by a deletion of 3/4 of the gal3 insertion sequence. The main conclusions are: (i) the stable, constitutive reversions of gal3 can arise by partial deletions of the insertion sequence, apparently by elimination of the nucleotide sequence which causes polarity; (ii) the chlD-pgl deletions may exhibit preferential termination at the right extremity of the gal3 insertion in presence of prophage lambda; and (iii) the gal3 insertion appears to inhibit the production of lambdagal particles by providing a nucleotide sequence which is recognized and degraded by a specific endonuclease. It is suggested that inhibition of transducing particle formation by gal3 and the preferred termination of deletions at gal3 might represent related phenomena.
Mol Gen Genet 1976 Dec 31
PMID:Reversion of the gal3 mutation of Escherichia coli: partial deletion of the insertion sequence. 77 85


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