Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Electrophysiological studies have shown that the olfactory organ (antennule) of the spiny lobster, Panulirus argus, has chemoreceptors that are selectively excited by adenine nucleotides in seawater. Biochemical studies have revealed that these same nucleotides can be rapidly dephosphorylated by ectoenzymes associated with the olfactory sensilla (aesthetascs). In this study the distribution of ecto-ATPase/phosphatase activity within aesthetascs was determined cytochemically and the nature of the adenine-nucleotide dephosphorylating activity was dissected biochemically. Cytochemically, the distribution of ATP-dephosphorylating activity was similar to that shown previously for AMP and beta-glycerol phosphate; i.e., cerium phosphate reaction product was specifically localized to the transitional zone where the sensory dendrites develop cilia and branch to form the outer dendritic segments. Unlike the dephosphorylation of AMP and beta-glycerol phosphate, Mg2+ or Ca2+ was required for ecto-ATPase/phosphatase activity. Biochemical measures of both AMP- and ATP-dephosphorylating activity within aesthetascs corroborated the cytochemical evidence that these activities are localized to the transitional zone. A major portion of the AMP dephosphorylation (about 67%) derives from nonspecific alkaline phosphatase activity that is insensitive to levamisole and L-bromotetramisole. In contrast, nonspecific phosphatase activity accounted for a much smaller part of the ATP dephosphorylation (about 15%). Ectoenzymatic activity in the transitional zone may be an important means of removing excitatory/inhibitory nucleotides from this region.
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PMID:Ecto-ATPase/phosphatase activity in the olfactory sensilla of the spiny lobster, Panulirus argus: localization and characterization. 133 Mar 15

Biochemical properties of topoisomerase I from normal and regenerating rat liver were analysed using crude or fractionated nuclear extracts. We could not detect significative change in topoisomerase I content or activity (magnesium stimulation and inhibition by ATP) during the course of liver regeneration. Topoisomerase I can be resolved into two species of 97 kDa and 100 kDa, with the same pI of 8.2-8.6 as shown by two dimensional gel electrophoresis. The two polypeptides contained a non-phosphorylated precursor and others forms with variable degrees of phosphorylation. In-vitro dephosphorylation with alkaline phosphatase leads to the disappearance of the phosphorylated forms and inactivation of the enzyme. The affinity of topoisomerase I for chromatin (measured by salt elution) differs markedly between normal and regenerating liver: nearly 50% of topoisomerase I remained bound to the chromatin from normal liver at 250 mM NaCl whereas it was completely eluted from 24-h-regenerating-liver nuclei. The biological significance of these results is discussed.
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PMID:Comparison of biochemical properties of DNA-topoisomerase I from normal and regenerating liver. 133 66

White male [correction of female] rats were given Dexamethasone in a single dose 0.35 mg/24 hrs. Group I was given the drug once, group II--received it for 2 days, and group III--for 7 days. 24 hrs after the medicine had been given the mucous membrane of the stomach corpus was collected for examinations. There were performed: H+E staining, PAS reaction and histochemical reaction to the activity of ATP-ase, acid phosphatase and alkaline phosphatase. The results obtained were compared with those obtained in a group of control animals which were given distilled water. The administration of Dexamethasone did not affect significantly the activity of the examined hydrolases, however, it damaged the mucous barrier of the stomach, specially in the animals after 7 days of application of the drug.
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PMID:[Histoenzymatic picture of rat gastric mucosa under the influence of dexamethasone]. 136 92

Female rats were given intragastrically, by means of a probe, Vibramycine in suspension, in a dose 4 mg/kg body weight, in different stages of pregnancy. On kidney sections there were performed: H+E staining, PAS reaction, histochemical determination of enzymes activity: alkaline phosphatase, ATP-ase, SDH and LDH. In non-pregnant females receiving the drug there was observed an intensification of alkaline phosphatase activity in brush border of main tubules of the kidney and a slight broadening of the light of the tubules. In pregnant females receiving the drug, most clearly in the second half of pregnancy a slight intensification of the activity of the examined enzymes was observed.
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PMID:[Histochemical picture of kidneys from pregnant female rats subjected to the action of vibramycin]. 136 93

The rexA and rexB genes of bacteriophage lambda encode a two-component system that aborts lytic growth of bacterial viruses. Rex exclusion is characterized by termination of macromolecular synthesis, loss of active transport, the hydrolysis of ATP, and cell death. By analogy to colicins E1 and K, these results can be explained by depolarization of the cytoplasmic membrane. We have fractionated cells to determine the intracellular location of the RexB protein and made RexB-alkaline phosphatase fusions to analyze its membrane topology. The RexB protein appears to be a polytopic transmembrane protein. We suggest that RexB proteins form ion channels that, in response to lytic growth of bacteriophages, depolarize the cytoplasmic membrane. The Rex system requires a mechanism to prevent lambda itself from being excluded during lytic growth. We have determined that overexpression of RexB in lambda lysogens prevents the exclusion of both T4 rII mutants and lambda ren mutants. We suspect that overexpression of RexB is the basis for preventing self-exclusion following the induction of a lambda lysogen and that RexB overexpression is accomplished through transcriptional regulation.
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PMID:The Rex system of bacteriophage lambda: tolerance and altruistic cell death. 137 78

1. Effect of intracellular ATP on Cl- current (ICl) mediated by the GABA (gamma-aminobutyric acid) receptor subtype, GABAA, was studied in dissociated nucleus tractus solitarii (NTS) neurones using the whole-cell mode of patch clamp. A concentration-jump technique termed 'Y tube' was used to rapidly apply agents externally. Dissociated neurones were obtained from 1- to 3-week-old rats. 2. When the patch-pipette solution contained 2 mM-ATP, the amplitude of ICl elicited by 10(-5) M-GABA did not show any time-dependent decrease (apparent run-down), for more than 60 min after the initial recording. In the presence of ATP, the half-maximum concentration (KD) and Hill coefficient calculated from the GABA concentration-response curve were 9.12 microM and 1.47, respectively. 3. In the absence of intracellular ATP, the amplitude of GABA-induced ICl decreased with time. The relative peak amplitudes after 20 and 60 min from the initial recording were 0.40 +/- 0.09 (n = 11) and 0.16 +/- 0.05 (n = 8) with respect to the initial response. 4. Removal of Mg2+ from the internal solution induced run-down of the GABA response even in the presence of 2 mM-intracellular ATP, suggesting that both intracellular ATP (2 mM or more) and Mg2+ are necessary to prevent run-down of the GABA response. 5. Activation of dephosphorylation processes by alkaline phosphatase (100-200 microM) did not affect the GABA response in neurones perfused with internal solution containing 2 mM-ATP and 3 mM-Mg2+. Blocking the dephosphorylation process by okadaic acid, a phosphatase inhibitor, did not prevent the run-down of the GABA response. 6. Calcium influxes passing through both the voltage-dependent L-type Ca2+ channel and the glutamate receptor-operated cation channel did not affect ICl induced by GABA. 7. GABA-induced ICl was also maintained by adding 2 mM-ADP or ATP gamma S (adenosine-5'-O-3-thiotriphosphate) to the internal solution containing Mg2+. Addition of 2 mM-adenosine, AMP, cyclic AMP, AMP-PNP (adenylimido-diphosphate) or ADP beta S (adenosine-5'-O-2-thiodiphosphate) to the internal solution did not prevent the run-down of the GABA response even in the presence of 3 mM-intracellular Mg2+. Based on the chemical specificity of these ATP analogues, it is suggested that there is an ATP-sensitive binding site (ATP receptor) in the cytoplasmic side of the cell membrane.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Direct modulation of GABAA receptor by intracellular ATP in dissociated nucleus tractus solitarii neurones of rat. 138 52

Placental alkaline phosphatase (PLAP) belongs to a class of proteins that are anchored to the plasma membrane by a COOH-terminal phosphatidylinositol-glycan (PI-G) moiety. Nascent forms of such proteins undergo NH2- and COOH-terminal processing to yield the mature PI-G-tailed proteins. We previously introduced a shortened engineered form of preproPLAP (preprominiPLAP) that permits monitoring in cell-free preparations its sequential processing to the pro form and then to the mature PI-G-tailed form. Previous studies were carried out by synthesizing the preproprotein cotranslationally in the presence of rough microsomal membranes (RM). Because of the complexity of the cotranslational system it was not possible to determine whether cofactors were required for processing. We have now prepared RM that are preloaded with prominiPLAP but contain little mature PI-G-tailed miniPLAP. Maximal processing requires supplementation with both ATP and GTP. Inhibitors of PI-G biosynthesis do not affect processing. Since cleavage and PI-G addition are presumably catalyzed by a transamidase, the nucleoside triphosphate requirements suggest that there are additional steps in prominiPLAP processing prior to transamidation with PI-G. These may involve translocation of the pro protein in a proper conformational state to the transamidase site.
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PMID:Phosphatidylinositol-glycan (PI-G)-anchored membrane proteins: requirement of ATP and GTP for translation-independent COOH-terminal processing. 138 69

ODC was purified to homogeneity from E. coli K12 MG1655 strain transformed with a pBR322 plasmid carrying the ODC gene. This preparation was homogeneous as it was analyzed by SDS-polyacrylamide gel electrophoresis. From this preparation the amino-terminal sequence analysis was obtained. The native ODC of E. coli is activated by ATP, GTP, CTP and UTP at 10(-3) M concentration to around 170-300%. Our results indicate that the recombinant ODC is activated only by GTP and UTP at 10(-3) M 370% and 300%, respectively. When the recombinant ODC was incubated with calf intestine alkaline phosphatase, this inactive ODC can be reversibly activated allosterically only by GTP or UTP at a concentration of 10(-6) or 10(-5) M. That GTP or UTP can allosterically convert the inactive form of ODC to an active form suggests that these analogues may be the in vivo physiological regulators of ODC.
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PMID:Allosteric activation by nucleotides of the inactive by phosphatase ornithine decarboxylase of Escherichia coli. 144 81

The localization of Ca(++)-ATPase activity was investigated in the rat cerebral cortex using an ultracytochemical method. Our cytochemical procedure for the detection of enzyme activity is based on an incubation medium consisting of tricine buffer, ATP-disodium salt as substrate, cerium chloride as capturing agent, CaCl2, and levamisole as a nonspecific alkaline phosphatase inhibitor. Final pH was 7.4. Reaction products showing Ca(++)-ATPase activity were localised on the pre- and postsynaptic plasma membrane in association with synaptic vesicles, postsynaptic dendrites and on the axolemma in myelinated nerve fibres. The verification of the main enzymatic properties of Ca(++)-ATPase localization activity is the subject of the following report.
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PMID:Enzyme ultracytochemical demonstration of Ca(++)-ATPase in the rat cerebral cortex. 144 75

Placental alkaline phosphatase (PLAP) has been used as a model for studying the biosynthesis of the phosphatidylinositol-glycan (PI-G)-protein linkage in intact cells and in cell-free systems. However, for the study of processing in cell-free systems, a small protein devoid of glycosylation sites is preferable. A PLAP-derived cDNA was engineered that codes for a nascent protein (mini-PLAP) of 28 kDa in which the NH2- and COOH-termini are retained but most of the interior of PLAP is deleted. In vitro translation of mini-PLAP mRNA in the presence of rough microsomal membranes yields mature PI-G-tailed mini-PLAP. Processing of nascent mutant proteins occurs only when a small amino acid is located at the site of cleavage and PI-G attachment (omega site). Mutations adjacent and COOH-terminal to the omega site have revealed that the omega + 1 site is promiscuous in its requirements but that only glycine and alanine are effective at the omega + 2 site. Rough microsomal membranes from T cells deficient in PI-G biosynthesis do not support processing of mini-PLAP; addition of exogenous PI-G restores activity. Translocation of the proprotein, most likely requiring ATP and GTP, precedes COOH-terminal processing.
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PMID:Placental alkaline phosphatase: a model for studying COOH-terminal processing of phosphatidylinositol-glycan-anchored membrane proteins. 145 93


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