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

The phosphorylation of lysine-rich histones F1, F2a2 and F2b of calf thymus has been investigated using homogeneous histone kinase from pig brain. 32P-labelled phosphopeptides from tryptic digests of corresponding histones were obtained. According to N-terminal analysis and the quantitative determination of amino acid composition of the obtained radioactive peptides the sites of phosphorylation were identified in the primary structure of lysine-rich histones, namely, Ser-38 for the polypeptide chain of histone F1, Ser-19 or 18 for histone F2a2 and Ser-14 and 36 for histone F2b. Thus, the high specificity of brain histone kinase in vitro was demonstrated.
Mol Biol (Mosk)
PMID:[Phosphorylation of lysine-rich histones by swine brain histokinase]. 18 71

Iodoacetamide, N-ethylmaleimide, p-hydroxymercuribenzoate (p-MB) and HgCl2 were tested as inhibitors of microsomal glucose-6-phosphatase. Iodoacetamide had no effect at 2 mM. N-ethylmaleimide inhibited only crude, but not purified microsomal preparations (M2) or crude microsomes exposed to deoxycholate. 14C-labelled N-ethylmaleimide was not bound by the M2 protein fraction. p-MB inhibited all types of preparations and the inhibition was not counteracted by detergent. A more detailed study was carried out with the purified M2 fraction (specific activity: 2-4 mumoles Pi/min/mg protein). Glucose-6-phosphate hydrolysis was inhibited 50% by 5 X 10(-5) M p-MB. The inhibition was completely reversible by dithiothreitol except when the enzyme was pre-incubated with p-MB in the absence of substrate. Then p-MB accelerated the temperature-dependent inactivation of glucose-6-phosphatase. Binding studies showed that around 3 mumoles 14C-p-MB were incorporated into 100 mg M2 protein regardless of the concentration of mercurial in the incubation mixture. That is, over a 25 fold range of p-MB concentration, causing up to 80% inhibition of enzyme activity, no difference was seen in the amount of labelled p-MB which was irreversibly bound to M2 protein. Kinetically p-MB behaved like a reversible inhibitor and this was confirmed by dilution experiments. Several compounds, including some amino acids, antagonized the inhibition by p-MB. The order of effectiveness was EDTA greater than barbital greater than tryptophan greater than histidine greater than lysine greater than other amino acids. Glycine, Tris and urea were ineffective competitors of p-MB inhibition. Double reciprocal plots showed that the Km for glucose-6-phosphate was increased and the Vmax reduced in the presence of p-MB. HgCl2 was a more effective inhibitor than p-MB with a Ki of 6 X 10(-6) M. We conclude that a reaction of p-MB with M2 sulfhydryls does not play a part in the inhibition of enzyme activity. It is suggested that p-MB may interact with one or more amino acid side chains in such a way that enzyme conformation is altered.
Mol Cell Biochem 1976 Jul 30
PMID:The effect of p-hydroxymercuribenzoate and congeners on microsomal glucose-6-phosphatase. 18 75

1. A method is described for the preparation of isolated cells from guinea pig liver. This involved perfusion in situ, in the non-physiological direction, with collagenase. 2. The cell yield was 20--30%, comparable with those from the livers of other species. 3. The ratio of lactate dehydrogenase to glutamate dehydrogenase in the cells was similar to that in vivo, indicating that there was negligible leakage of cytoplasmic enzymes. 4. The concentrations of K+ and adenine nucleotides were initially lower than in the perfused liver; normal values were obtained on incubation, particularly in the presence of substrate. 5. The L-lactate: pyruvate ratio is 16:1, close to established values. The total beta-hydroxybutyrate: acetoacetate ratio indicates that the mitochondrial redox state is more oxidised than in the perfused liver, but the intracellular ratio is similar to that of the intact liver. 6. Rates of gluconeogenesis and ureogenesis, are within the physiological range. Maximal gluconeogeneis from L-lactate was preceded by a lag period. L-lysine stimulated glucose production from L-lactate but did not abolish the lag phase. 7. The effects of aminooxyacetate and octanoate on L-lactate gluconeogenesis were similar to those in the perfused liver.
Mol Cell Biochem 1977 May 31
PMID:Preparation and characterization of isolated parenchymal cells from guinea pig liver. 19 81

The effect of three naturally occurring polyamines (putrescine, spermidine, and spermine) on the activity of rabbit skeletal muscle phosphorylase phosphatase was investigated. Only spermine significantly inhibited the enzyme. The mode of inhibition (ki value of 0.3 mM) of the phosphatase by spermine appears to be different from that caused by divalent metal ions or by other organic cations, such as arginine and lysine esters, since it is noncompetitive with respect to the substrate, phosphorylase a.
Mol Cell Biochem 1977 Apr 12
PMID:Inhibition of rabbit skeletal muscle phosphorylase phosphatase by spermine. 19 99

Chemical modification of pig heart ferricytochrome C by the paramagentic analog of N-acetylimidazole-N-(2,2',5,5'-tetramethyl-3-carboxypyrroline-1-oxyl)-imidazole has been studied. Two main modified preparations, both with the single spin label per molecule, have been isolated by means of chromatography on CM-Sephadex C-25. The study of UV-difference spectra of the SL-preparations versus native Cyt C, the spectrophotometric titration of the tyrosine residues in modified proteins and the study of their reaction with hydroxylamine allow to conclude that one of these preparations (fraction II) is lysine modified Cyt C-SL(Lys)-Cyt C and the other (fraction III) is tyrosine modified protein-SL(Tyr)-Cyt C. From the present results and the data available in literature the most probable location of the modification sites in the three-dimentional structure of Cyt C is Tyr-74 in SL (Tyr)-Cyt C and one of the neighbouring lysil residues Lys 72 or Lys 73 in SL (Lys)-Cyt C on the molecular surface. From the absorbtion and CD-spectra of the modified and native Cyt C in the spectral interval 190--450 nm and from the high resolution PMR data the conclusion has been made that the chemical modification does not alter the immediate vicinity of the heme group and the molecular structure of Cyt C as a whole. Therefore both SL-modified preparations might be useful for the conformational and functional investigations of Cyt C.
Mol Biol (Mosk)
PMID:[Chemical modification of ferricytochrome c by N-(2,2',5,5'-tetramethyl-3-carboxypyrroline-1-oxyl)-imidazole]. 21 5

The influence of a specific histone kinase, phosphorylating lysin-rich histone H1, H2a, H2b on the physico-chemical properties of chromatin from hepatocytes of normal and hepatectomized guinea pigs has been investigated. A cytochemical method has been used which permits to obtain information about the physico-chemical properties of the chromatin in situ, i.e. without its isolation. This approach allows us to evaluate changes in chromatin properties in cell cultures as well as in the intact organism. It is found that the specific histone kinase changes the properties of chromatin in non-dividing cells bringing about an increase of acridine orange binding to the level characteristic for hepatocytes after partial hepatectomy. At the same time the chromatin properties in activated hepatocytes are not changed under the action of the histone kinase. It is concluded that the specific histone kinase, phosphorylating lysine-rich histones can play an important role in the course of chromatin activation in cells stimulated to proliferation.
Mol Biol (Mosk)
PMID:[Influence of histone kinase phosphorylating lysine-rich histones, on the physico-chemical properties of normal hepatocyte chromatin and after partial hepatectomy]. 22 34

The chromatin core particle DNA conformation deduced in broad outline by Finch et al. [Finch, J. T., Lutter, L. C., Rhodes, D., Brown, R. S., Rushton, B., Levitt, M. & Klug, A. (1977) Nature 269, 29-36] can be described in detail using other available experimental results. Histone binding sites compatible with the pattern of pancreatic DNase I digestion (Simpson, R. T. & Whitlock, J. P., Jr. (1976) Cell 9, 347-353; Noll, M. (1977) J. Mol. Biol. 116, 49-71; Lutter, L. C. (1977) J. Mol. Biol. 117, 53-69] lend to core particle DNA pseudosymmetry characteristic of molecular point group D(3). DNA symmetry and pseudosymmetry, in turn, imply equivalence and quasi-equivalence properties of the histone packing arrangement that support the following deductions: (i) One and only one alpha(2)beta(2) histone tetramer, presumably (H3)(2)(H4)(2), can serve as a stable subassembly within the histone octamer. (ii) There is a unique, strand-specific way to assign DNA binding domains to the arginine-rich histones (H3 and H4). (iii) Histones H3 and H4 alone should suffice to impose a supercoiled structure on DNA, as is observed experimentally, because only the tetramer can mimic a screw dislocation and thereby complement the screw symmetry of the DNA supercoil. (iv) The two slightly lysine-rich histones H2A and H2B are probably responsible, each in a different way, for dividing the eukaryotic chromatin fiber into discrete subunits. (v) The proposed arrangement of four distinct proteins appears to be a minimum formal requirement for making nucleosomes; that is, for introducing regularly spaced supercoiled DNA folds without also allowing formation of an indefinitely long (and genetically inert) DNA superhelix.
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PMID:Histone packing in the nucleosome core particle of chromatin. 27 80

Eight strains devoid of homocitrate synthase activity were found among lysine requiring mutants of the yeast Saccharomycopsis lipolytica. Genetic analysis of these strains showed that they were all affected at the same locus LYS 1. Three lines of evidence suggest that this locus defines a structural gene for homocitrate synthase. First, the mutations show various degrees of intragenic complementation; it could be shown in some cases that the hybrid enzyme formed in vivo displayed modified properties in vitro. Second, reversion of some of these mutations can result in a modified enzyme (desensitized). Third, a feedback mutant of homocitrate synthase was directly isolated from the wild type strain, and shown to carry a single mutation at of near LYS 1. We also present here the first attempts at genetic fine mapping in Saccharomycopsis lipolytica.
Mol Gen Genet 1979 May 04
PMID:Evidence for mutations in the structural gene for homocitrate synthase in Saccharomycopsis lipolytica. 28 93

The ribosomal proteins of 11 mutants which are sensitive to starvation at elevated temperature and of 36 transductants derived from them were studied with several electrophoretic, immunochemical and proteinchemical methods. The following results were obtained: (1) Ribosomal protein S8 is altered in three of these mutants. (2) The amino acid exchange in proteins S8 of mutant N4128 is Glu leads to Lys in position 59 of the protein chain. (3) Temperature sensitivity and inability to recover from starvation at elevated temperatures are caused by the same mutational event which is, however, unrelated to the alteration in protein S8. Several electrophoretic and immunological procedures were applied during the characterization of these mutants. A modified immunoelectrophoresis on cellulose acetate gels was developed, and proved to be the most applicable procedure for the detection of mutationally altered ribosomal proteins. This procedure may gain general importance for detecting mutational alterations in other proteins.
Mol Gen Genet 1977 Dec 30
PMID:Improved electrophoretic and immunochemical techniques for the identification and characterization of mutant proteins, applied to ribosomal protein S8 in Escherichia coli mutants. 34 Sep 33

When studying mutants affecting lysyl-tRNA synthetase or tRNAlys (hisT, hisW), a lack of correlation is clearly observed between the amount of lysyl-tRNA and the level of derepression of several lysine biosynthetic enzymes. This exlcudes the possible role of lysyl-tRNA as the specific corepressor of the lysine regulon. However, the level of derepression of DAP-decarboxylase, the last enzyme of the lysine pathway, is very low in the hisT mutant; this indicates that tRNAlys is a secondary effector involved in the regulation of the synthesis of this enzyme.
Mol Gen Genet 1978 Feb 07
PMID:Effect of mutations affecting lysyl-tRNAlys on the regulation of lysine biosynthesis in Escherichia coli. 34 82


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