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)

1. The urinary excretion of inorganic pyrophosphate (PPi), a known inhibitor of the growth and aggregation of crystals of calcium phosphate and calcium oxalate, increases after ingestion of orthophosphate (Pi). This effect may contribute to the apparent ability of oral phosphate to reduce the formation of urinary stones in man. This paper is a study of the mechanism by which Pi increases PPi excretion, investigated by renal clearance techniques in man and renal arterial infusion in dogs. PPi in plasma was measured by an isotope-dilution method after ion-exchange chromatography. 2. The mean renal clearance of endogenous PPi in ten men was 7-9 +/- 1-7 (SE) ml/min, and the mean ratio of PPi clearance to creatinine clearance was 0-08 +/- 0-02 (SE). The oral ingestion of Pi increased the urinary excretion and renal clearance of PPi about threefold, without significantly changing its concentration in plasma. 3. In dogs, the infusion of Pi into one renal artery caused a greater increase in urinary PPi from the infused than from the non-infused kidney, an effect that could be accentuated by simultaneous intravenous infusion of PPi. In dogs, only 1-3% of an injected or infused dose of PPi appeared intact in the urine, regardless of whether it was infused into the systemic or renal circulation. 4. These results suggest that Pi has a direct affect on the kidney to increase the excretion of PPi. It is possible that Pi either interferes with tubular reabsorption of PPi, perhaps by competing for a common tubular transport mechanism, or that Pi diminishes the intrarenal hydrolysis of PPi.
Clin Sci Mol Med 1976 Nov
PMID:The influence of orthophosphate on the renal handling of inorganic pyrophosphate in man and dog. 18 25

1. The pyruvate dehydrogenase complex from human heart has been partially purified and shown to be regulated by a phosphorylation-dephosphorylation cycle similar to that previously found for other mammalian tissues. 2. Incubation of the complex with ATP (2 mmol/1) led to its inactivation associated with the concomitant incorporation into the protein of 32P from the terminal phosphate group of the ATP. Pyruvate, ADP, thiamin pyrophosphate and dichloroacetate diminished the rate of inactivation by ATP. 3. Pyruvate dehydrogenase phosphatase from human heart requires Mg2+ for activity and is sensitive to Ca2+ at concentrations of a few mumol/1. Similar ionic requirements of the skeletal muscle phosphatase have been demonstrated in a crude tissue extract. 4. The activity of pyruvate dehydrogenase in human adipose tissue was less than 10% of typical values in rats. This could be due to the high level of dietary fat consumed by humans, which is known to repress the enzyme activity in rats.
Clin Sci Mol Med 1976 Nov
PMID:Regulation of the human pyruvate dehydrogenase complex. 18 26

In Chlamydomonas reinhardi, mutations in either of two unlinked genes (PD2 and PD3) abolish the activity of the derepressible neutral phosphatase. The question arose whether these genes (or one of them) specify the structure of the enzyme or whether they have a regulatory function. Three mutants producing an active phosphatase at 25 degrees C but not at 35 degrees C were isolated and investigated. One of these mutants (PDts11) was allelic with PD2, another one (PDts12) was linked to PD3 and the third one (PDts13) was linked to PD2. PDts11 and PDts13 affected the formation of the neutral phosphatase only whereas PDts12 interfered with the formation of both neutral and alkaline phosphatases at 35 degrees C. The neutral phosphatase produced by the three mutants at low temperature was not more thermosensitive in vitro than the wild enzyme. Moreover, quite similar Km values were found in WT, PDts11 and PDts12 using naphthyl phosphate as a substrate. On the other hand, revertants of PD-2 and PD-3 were isolated: their neutral phosphatases could not be distinguished from the wild enzyme on the basis of their thermosensitivities and Km values for naphthyl phosphate. These results are consistent with the idea that PD2 and PD3 are regulatory genes. Other possible regulatory genes were revealed through PDts12 and PDts13 mutations.
Mol Gen Genet 1976 Nov 17
PMID:Genes involved in the regulation of the neutral phosphatase in Chlamydomonas reinhardi. 18 76

Experimental evidence for the presence and biosynthesis of subviral, leukemogenic particles in the isolated mitochondria of spleen cells of mice infected with Rauscher murine leukemia (RML) virus is presented. These subviral particles sediment at a density of 1.27-1.29 g/ml and induce splenomegaly and RML three weeks after i.v. or i.p. administration to white mice. Virosomes have been labelled with [32P]phosphate in the isolated mitochondria from RML spleen cells and high molecular weight (70S) [32P]RNA has been isolated from these subviral, leukemogenic particles. Rauscher virus group specific antigens were detected by immunodiffusion in the inner membrane and matrix fraction of the mitochondria of RML spleen cells. These results together with our earlier findings strongly suggest that mitochondria of the transformed cells participate in the biosynthesis of RNA tumor viruses. Possible mechanism of the penetration of viral genetic information of RNA tumor viruses into mitochondria of tumor cells in vivo is discussed.
Mol Cell Biochem 1977 Feb 04
PMID:Biosynthesis of subviral oncogenic particles (virosomes) in mitochondria of Rous sarcoma and Rauscher murine leukemia cells. 19 96

The abilities of purine- and pyrimidine-requiring mutants to produce six orthophosphate repressible extracellular enzymes, alkaline phosphatase, 5'-nucleotidase, acid phosphatase, two nucleases and ribonuclease N1 were examined by culturing these mutants in low and high phosphate media containing nucleotide or nucleoside. All the purine requiring mutants produced significantly reduced amounts of alkaline phosphatase, 5'-nucleotidase, acid phosphatase, alkaline nuclease and acid nuclease ranging 0.5-4.2, 5.0-17.4, 25.0-100, 20.3-67.5 and 6.2-48.5%, respectively. Production of ribonuclease N1 was found to be rather stimulated (150-564%) in these mutants. Essentially the same results were obtained for pyrimidine requiring mutants. Among those mutants ad-2 and ad-9 showed relatively high enzyme producing activity. Especially the production of ribonuclease N1 in ad-2 and ad-9 ranged to 4.9- and 5.6-fold that in the wild type. Though nuc-1 mutant (A1) has no ability to produce all these six repressible enzymes, double mutants A1ad-2 and A1ad-9 produced a significant amount of ribonuclease N1 in low and high phosphate media and acid phosphatase in low phosphate media.
Mol Gen Genet 1977 Feb 28
PMID:Control of the Production of orthophosphate repressible extracellular enzymes in Neurospora crassa. 19 39

Liver cells were prepared from rats fed a rachitogenic diet to investigate the hepatic metabolism of [alpha-1,2-3H2] vitamin D3. Rat hepatocytes suspended in Hanks medium rapidly took up labeled vitamin D3 from the incubation medium and converted this sterol to various metabolites, including 25-hydroxy vitamin D3 (25-OH-D3). There was steady increment in the cellular production of 25-OH-D3 and of the more polar metabolites of vitamin D3 over 3 hr of incubation as determined by thin layer chromatography. Neither the addition of cyclic nucleotides or dexamethasone to, nor the removal of calcium or phosphate from the medium resulted in changes in the rate of conversion of vitamin D3 to its products. Rats pretreated with sodium diphenylhydantoin converted labeled vitamin D3 to its metabolites at the same rate as control rats. These data indicate that isolated liver cells retain the capacity for vitamin D3 hydroxylation, but suggest that the rate of this process does not undergo rapid changes in response to metabolic stimulation.
Mol Cell Biochem 1977 May 03
PMID:In vitro metabolism of vitamin D3 by isolated liver cells. 19 79

Cyclic AMP (300 micron) activates phosphofructokinase from dialyzed haemolysates of mature rat erythrocytes. The main conclusions are: a) Cyclic AMP, at pH 7.1 and low concentrations of fructose-6-phosphate, is able to reverse the inhibition produced by different amounts of ATP (up to 1.5 mM). b) The cyclic nucleotide is a positive allosteric effector of the enzyme as shown by the displacement of sigmoidal fructose-6-phosphate saturation curve to hyperbolic kinetics in the presence of inhibitory concentrations (1.5 mM) of ATP.c) Cyclic AMP has no significant influence as deinhibitor of phosphofructokinase either at pH 7.1 and non-inhibitory levels (0.25 mM) of ATP or at pH 8.1 and inhibitory (1.5 mM) or non-inhibitory (0.25 mM) concentrations of ATP. Similar conclusions were obtained with 300 micron AMP but not at a lower concentration (3 micron) with both nucleotides. The comparison of cyclic AMP result with those obtained under similar concentrations of AMP suggest that cyclic AMP is really only an "in vitro" modulator of the enzyme from rat erythrocytes, presumably at an AMP regulatory stie, since non-physiological concentrations are required to act as deinhibitor.
Mol Cell Biochem 1977 May 03
PMID:Activation of rat erythrocyte phosphofructokinase by AMP and by non-physiological concentrations of cyclic AMP. 19 80

The "in vivo" effects of L-phenylalanine on the gluconeogenic pathway in the liver of fasted rats with experimentally induced phenylketonuria-like characteristics have been investigated. Significant increases of the fructose 6-phosphate, glucose 6-phosphate and glucose concentrations were observed. The study of the effect of L-phenylalanine on the cytoplasmic and mitochondrial redox state and energy charge showed an increase in the mitochondrial NAD+/NADH ratio while the energy charge was virtually unchanged. The effects of phenylalanine and its metabolic derivatives (phenylacetate, phenylethylamine, phenyl-lactate, o-hydroxyphenylacetate and phenylpyruvate) on the activity of lactate dehydrogenase (EC 1.1.1.27), malate dehydrogenase (EC 1.1.1.37) and 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) in rat liver have been also investigated. Phenylpyruvate inhibited the lactate dehydrogenase activity with a Ki of 5.3 mM. Phenylpyruvate also inhibited both the mitochondrial (Ki = 4 mM) and cytoplasmic (Ki = 5 mM) malate dehydrogenase activities. Phenylpyruvate, phenylacetate and o-hydroxyphenylacetate inhibited the 3-hydroxybutyrate dehydrogenase activity with Ki values of 0.7, 6.0 and 9.5 mM respectively.
Mol Cell Biochem 1977 May 31
PMID:Experimental phenylketonuria: metabolic studies in rat liver. 19 83

When an aqueous solution (pH 7.0) of deoxythymidine 5'-phosphate, 4-amino-5-imidazolecarboxamide and cyanamide was dried and heated for 18 h at 60 degrees C, P1, P2-dideoxythymidine 5'-pyrophosphate (I) was formed in a 58% yield. Oligonucleotides were not detected in the reaction product. Under conditions employed in the above reaction, (I) was shown to be stable. In prebiotic polymerization reactions employing deoxythymidine 5'-triphosphate as the polymerizing species, (I) could therefore function as a primer and minimize the formation of cyclic nucleotides.
J Mol Evol 1977 Dec 29
PMID:Cyanamide mediated syntheses under plausible primitive earth conditions. I. The synthesis of P1, P2 dideoxythymidine 5'-pyrophosphate. 20 14

Calcium salts were found to replace ACTH in inducing steroidogenesis in isolated adrenocortical cells from rats. This Ca-specific stimulation occurred when the cation was presented to the cells in the presence of phosphate and carbonate as a counter-ions under conditions which favoured the formation of colloidal calcium. Colloid generation and stabilization was facilitated by the use of calcium buffers and gelatin. Stable soluble or sparingly soluble calcium complexes were inactive. The preparation of cells and metastable calcium solutions is described in detail. The Ca trigger was sensitive to Ca deprivation or inhibitors of Ca transport and could be replced by Sr. The relative role of Ca and cyclic AMP as second messengers is discussed.
Mol Cell Endocrinol 1978 Jan
PMID:Steroidogenesis in isolated adrenal cells: excitation by calcium. 20


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