Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.4.1 (phosphodiesterase)
18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The major aims of this study were to determine the degree of phospholipid asymmetry and the neighbor analysis of phospholipids in different types of cell membranes. For this study a penetrating probe (FDNB), a non-penetrating probe (TNBS) and a cross-linking probe (DFDNB) were used. The reaction of hemoglobin, membrane protein and membrane PE and PS of erythrocytes with DFNB and TNBS was studied over a concentration range of 0.5 to 10 mM probe. TNBS reacts to an extremely small extend with hemoglobin over the concentration range 0.4 to 4 mM whereas FDNB reacts with hemoglobin to a very large extent (50 fold more than TNBS). The reaction of membrane protein of intact erythrocytes reaches a sharp plateau at 1 mM TNBS whereas the reaction of membrane protein goes to a much larger extent with FDNB with no plateau seen up to 4 mM FDNB. This data shows that TNBS does not significantly penetrate into the cell under our conditions whereas FDNB does penetrate into the cell. The results show that there are four fold more reactive sites on proteins localized on the inner surface of the erythrocyte membrane as compared to the outer surface. TNBS at 0.5 to 2 mM concentration does not label membrane PS and labels membrane PE to a small extent. The reaction of PE with TNBS shows an initial plateau at 2 mM probe and a second slightly higher plateau between 4 to 10 mM probe. TNBS from 0.5-2.0 mM does not react with PS, but between 3 to 10 mM concentration, a very small amount of PS reacts with TNBS. Hence above 2 mM TNBS or FDNB a perturbation occurs in the membrane such that more PE and PS are exposed and react with these probes. These results demonstrate that essentially no PS is localized on the outer surface of the membrane and only 5% of the total membrane PE is localized on the outer surface of the erythrocyte membrane. TNBS and FDNB were reacted with yeast, E. coli, and Acholeplasma cells. With yeast cells, FDNB reacts to a much larger extent with PE than does TNBS, indicating that FDNB penetrates into the cell and labels more PE molecules. With E. coli, but not with erythrocytes or yeast cells, phospholipase A activity was very pronounced at pH 8.5 giving rise to a large amount of DNP-GPE from DNP-PE. A phosphodiesterase was also present which hydrolyized DNP-GPE to DNP-ethanolamine. The multilayered structure of the E. coli cell envelop did not permit a definitive interpretation of the results. It is clear, however, that TNBS and FDNB react to a different extent with PE in this cell. The Acholeplasma membrane had no detectable PE or PS but contains amino acid esters of phosphatidylglycerol. The reaction of these components with TNBS and FDNB indicate that these aminoacyl-PG are localized on both surfaces of the membrane, with 31% being on the outer surface and 69% on the inner surface...
...
PMID:Differential reaction of cell membrane phospholipids and proteins with chemical probes. 0 64

Frog (Rana catesbiana) rod outer segment disc membranes contain a cyclic nucleotide phosphodiesterase (EC 3.1.4.17) which is activated by light in the presence of ATP. This enzyme is firmly bound to the disc membrane, but can be eluted from the membrane with 10 mM Tris-HCl buffer, pH 7.4 and 2 mM EDTA. The eluted phosphodiesterase has reduced activity, but can be activated approximately 10-fold by polycations such as protamine and polylysine. The eluted phosphodiesterase can no longer be activated by light in the presence of ATP, that is, activation by light apparently depends on the native orientation of phosphodiesterase in relationship to other disc membrane components. The eluted phosphodiesterase was purified to homogeneity as judged by analytical polyacrylamide gel electrophoresis and polyacrylamide gel isoelectric focusing. The over-all purification from intact retina was approximately 925-fold. The purification of phosphodiesterase from the isolated rod outer segment preparation was about 185-fold with a 28% yield. Phosphodiesterase accounts for approximately 0.5% of the disc membrane protein. The eluted phosphodiesterase (inactive form) has a sedimentation coefficient of 12.4 S corresponding to an approximate molecular weight of 240,000. Sodium dodecyl sulfate polyacrylamide gel electrophoresis separates the purified phosphodiesterase into two subunits of 120,000 and 110,000 daltons. With cyclic 3':5'-GMP (cGMP) as substrate the Km for the purified phosphodiesterase is 70 muM. Protamine increases the Vmax without changing the Km for cGMP. The isoelectric point (pI) of the native dimer is 5.7. Limited exposure of the eluted phosphodiesterase (inactive form) to trypsin produces a somewhat greater activation than is obtained with 0.5 mg/ml of protamine. The trypsin-activated phosphodiesterase has a sedimentation coefficient of 7.8 S corresponding to an approximate molecular weight of 170,000. The 110,000-dalton subunit is much less sensitive to trypsin hydrolysis and the 120,000-dalton subunit is rapidly replaced by smaller fragments. On the basis of the molecular weight of the purified phosphodiesterase (240,000) and the concentrations of phosphodiesterase and rhodopsin in the rod outer segment, it is estimated that the molar ratio ophosphodiesterase to rhodopsin in the rod outer segment is approximately 1:900. Since all of the disc phosphodiesterase molecules are activated when 0.1% of the rhodopsins are bleached, we conclude that in the presence of ATP 1 molecule of bleached rhodopsin can activate 1 molecule of phosphodiesterase.
...
PMID:Purification and properties of the light-activated cyclic nucleotide phosphodiesterase of rod outer segments. 16 36

Experiments with cold exposure confirmed previous studies indicating that the endogenous protein acitvator of phosphodiesterase (PDEA) isolated by Cheung participates in the in vivo regulation of 3':5'-cyclic adenosine monophosphate (cAMP) in adrenal medulla. This activator of cAMP phosphodiesterase (PDE) (3':5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17) is present in the particulate as well as the soluble fractions of rat brain. It was found that a purified cAMP-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37), in the presence of ATP and cAMP, stimulates 3-fold the release of PDEA from the particulate fraction of rat brain and adrenal medulla. The substrate for this phosphorylation could be either a membrane protein that binds PDEA or PDEA itself. In vivo evidence, however, obtained by injecting rats intraventricularly with [gamma-32P]ATP, indicates that the PDEA does not contain radioactive phosphate in its structure. Also, PDEA could not be phosphorylated by protein kinase in vitro. The following mechanism is postulated: when the intracellular content of cAMP increases it activates a protein kinase which phosphorylates a PDEA-binding membrane protein and releases PDEA. In turn this binds to activator-deficient high Km PDE and decreases its Km to facilitate the hydrolysis of the increased concentration of cAMP.
...
PMID:Regulation of transsynaptically elicited increase of 3':5'-cyclic AMP by endogenous phosphodiesterase activator. 17 3

Protein kinase, phosphodiesterase and adenylate cyclase of plasma membrane of adipocytes and the effect of the feedback regulator (FR) on these three enzymes was measured and compared. The basal level ratio of adenylate cyclase to phosphodiesterase to protein kinase was 1:1.9:3.0. Epinephrine and/or FR alters this ratio. FR stimulated protein kinase activity up to 3 fold in the presence of a wide range of enzyme concentrations, 5-50 mug membrane protein/tube. The concentration of FR effective for stimulation of membrane protein kinase was much greater than that needed for inhibition of adenylate cyclase and phosphodiesterases. The inhibition by FR on adenylate cyclase was the most potent effect among the 3 enzymes. 1 U (or 2 U/ml) of FR inhibited 50% of the adenylate cyclase activity in a defined system. The maximum effective concentration of FR for stimulation of membrane protein kinase was greater than 10 U/ml. Histone type 11A was the best substrate for protein phosphorylation so far observed. The FR stimulatory effect was observed at all substrate concentrations used ranging from 1-5 mg/ml. A NaF concentration curve shows that 15 mM NaF gave maximum phosphorylation. The stimulatory effect of FR was observed both in the presence and absence of NaF. Protein kinase of adipocyte plasma membrane was mainly cAMP-independent. The effect of FR (20 U/ml) in stimulation of protein phosphorylation was much greater than that of cAMP (1 X 10(-6) M). The cAMP and FR effects seemed to be additive. Preincubation of plasma membrane with FR in the absence of ATP resulted in no decrease but slight increase in protein kinase activity. A shift in protein kinase, phosphodiesterase and adenylate cyclase ratios by FR suggests the regulatory role of FR in cAMP metabolism in adipocytes.
...
PMID:Influence on adipocyte plasma membrane bound protein kinase by feedback regulator. 17 96

Numerous drugs and chemicals affect the function of human blood platelets. The mechanism of action of some medications is partly understood. Aspirin is the most frequently involved drug. It appears to interfere with the platelet release reaction by acetylation of a platelet membrane protein which may be involved in the synthesis of prostaglandins. Other anti-inflammatory drugs, including indomethacin, phenylbutazone, ibuprophen (Motrin) and clonixin, also interfere with the release reaction but have a shorter acting course than aspirin. Some drugs stimulate adenylcyclase (gliclazide) or block phosphodiesterase, (dipyridamole, caffeine) both of which actions lead to an increase in adenosine cyclic 3':5' monophosphate (cAMP) and decrease aggregation by adenosine diphosphate (ADP). These interactions should be known to clinical scientists since patients using these medicaments may manifest abnormal platelet function tests in the laboratory and mild hemorrhagic syndromes in the clinic.
...
PMID:Effects of drugs on platelet function. 18 70

Some of the acute actions of insulin may be mediated by an enzyme-modulating inositol phosphate glycan, produced by the insulin-sensitive hydrolysis of glycosyl-phosphatidylinositol (GPI) that is structurally similar to a membrane protein anchor. An inositol glycan fragment from the structurally characterized Trypanosoma brucei variant surface glycoprotein GPI anchor is evaluated for insulin-mimetic antilipolytic activity. The fragment specifically and dose-dependently inhibits isoproterenol-stimulated lipolysis. Like the effect of insulin, glycan-induced antilipolysis is blocked by the low Km cAMP phosphodiesterase inhibitor imazodan (CI-914) and the serine/threonine phosphatase inhibitor, okadaic acid, suggesting that the activation of both cAMP phosphodiesterase and serine/threonine protein phosphatases are necessary. Moreover, this fragment causes a specific and dose-dependent inhibition of both microsomal glucose-6-phosphatase (EC 3.1.3.9) and cytosolic fructose-1,6-bisphosphatase (EC 3.1.3.11) activity. Additionally, direct addition of the glycan to hepatocytes caused marked inhibition of glucose production from pyruvate. These results suggest that the direct modification of the activities of these two gluconeogenic enzymes by an inositol glycan may play a role in the inhibition of glucose output by insulin and provide the first evidence for the insulin-mimetic properties of a chemically characterized inositol glycan.
...
PMID:An inositol phosphate glycan derived from a Trypanosoma brucei glycosyl-phosphatidylinositol mimics some of the metabolic actions of insulin. 132 96

1. In this paper we report the results of studies on an adenylyl transferase (AyTase) activity from Dictyostelium discoideum. 2. Previous studies suggested that this activity catalyzed the transfer of AMP from ATP to a membrane protein to form a phosphoamidate reaction product. 3. In the present study we have isolated and characterized the product of the AyTase reaction and surprisingly found two AMP labeled products by SDS-gel-filtration HPLC. 4. The apparent molecular weights of these phosphoamidates were 13.5 and 1.5 kDa. 5. In addition, because the reaction product was rapidly degraded by a phosphoamidase, experiments were undertaken using AVAMP, a synthetic phosphoamidate, as an alternative phosphoamidase substrate, to trap the reaction products. 6. As the phosphoamidase activity could be inhibited by cAMP, cyclic formycin monophosphate, an analog of cAMP resistant to hydrolysis by cAMP phosphodiesterase, was also used to trap the products. 7. Both attempts at trapping failed. 8. A model for the AyTase reaction was developed to account for the failure to trap the products and the formation of two phosphoamidates.
...
PMID:Isolation and characterization of the protein phosphoamidates formed by a membrane bound adenylyl transferase reaction in Dictyostelium discoideum. 164 17

A 32P-labeled protein that co-purified with acidic fibroblast growth factor (aFGF) receptor from bovine liver proved to be a distinct membrane protein, which itself has kinase activity that is stimulated by aFGF. The protein was designated MAFP for major aFGF-stimulated phosphoprotein. MAFP was purified from bovine liver using immunoaffinity chromatography with monoclonal antibody to MAFP following Triton X-100 extraction of plasma membranes and wheat germ lectin-Sepharose 4B column chromatography. The purified MAFP showed molecular masses of 130 kDa and 260 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions, respectively. Purified MAFP elicited aFGF-stimulated Thr-specific autophosphorylation activity and phosphorylation activity toward protein substrates (myelin basic protein and histone). Amino acid sequence analyses of 16 peptide fragments of MAFP, produced by endoproteinase Lys-C digestion followed by reduction and S-pyridylethylation, showed approximately 80-100% homology with the cDNA-deduced amino acid sequences of human and mouse plasma cell membrane glycoprotein, PC-1 (Buckley, M. F., Loveland, K. A., McKinstry, W. J., Garson, O. M., and Goding, J. W. (1990) J. Biol. Chem. 265, 17506-17511), suggesting that MAFP is the bovine version of PC-1. The amino acid sequences of bovine MAFP, human and mouse PC-1 reveal a putative ATP binding site in their extracellular domains. These results suggest that MAFP(PC-1) is an ectoprotein kinase. In addition to the kinase activity, MAFP(PC-1) was also found to possess alkaline nucleotide phosphodiesterase activity. It is now clear that several of the unique properties previously attributed to the aFGF receptor kinase are actually properties of this novel Thr-specific ectoprotein kinase, which co-purifies with the aFGF receptor and is responsive to stimulation by aFGF.
...
PMID:The plasma cell membrane glycoprotein, PC-1, is a threonine-specific protein kinase stimulated by acidic fibroblast growth factor. 171 69

Treatment of NG108-15 cells in culture with the opiate peptide [D-Ala2,D-Leu5]enkephalin produces maximal inhibition of cyclic AMP synthesis in less than 15 min. The activity of [GM3]:N-acetylgalactosaminyltransferase is similarly inhibited, but maximal inhibition is not observed for at least 30 min following the addition of [D-Ala2,D-Leu5]enkephalin. Conversely, the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine rapidly potentiates the intracellular accumulation of cyclic AMP and, in a more gradual fashion, increases [GM3]:N-acetylgalactosaminyltransferase activity. The reductions in the activity of [GM3]:N-acetylgalactosaminyltransferase that occur following treatment of NG108-15 cells with indomethacin argues for a direct role of cyclic AMP in the observed changed in [GM3]:N-acetylgalactosaminyltransferase activity. By adding low concentrations of cyclic AMP (but not cyclic GMP) to microsomes derived from neonatal rat brain, we were able to demonstrate a dose-dependent phosphorylation of membrane protein and subsequent doubling of [GM3]:N-acetylgalactosaminyltransferase activity.
...
PMID:Direct demonstration of the activation of UDP-N-acetylgalactosamine: [GM3]N-acetylgalactosaminyltransferase by cyclic AMP. 242 Sep 36

Plasma membrane has been prepared from pea seedlings in the presence of [ethylenebis(oxyethylenenitrilo)]tetraacetic acid (EGTA). Calmodulin has been detected in these plasma membrane preparations using calcium overlay techniques, immunoblots, quantitation with antibodies raised against spinach calmodulin, phosphodiesterase activation, mobility shift, and heat stability. EGTA-stable calmodulin represents 0.5-1% of the total plasma membrane protein, and it is the only detectable calcium-binding protein in plasma membrane isolated under these conditions. The anti-spinach calmodulin reacts only with the N-terminal region of spinach calmodulin representing residues 1-106. The positioning of EGTA-stable calmodulin in the plasma membrane has been probed with trypsin and anti-spinach calmodulin. The data suggest that the calmodulin N-terminal region representing residues 1-106 projects from the membrane and could be available for binding other proteins. Calcium-dependent calmodulin binding to the plasma membrane has also been detected. Calcium-dependent calmodulin-binding proteins have been characterized using calmodulin overlay methods. The exposure of calmodulin-binding domains of most of these proteins from the plasma membrane is further suggested by their reaction with azidoiodinated calmodulin.
...
PMID:The location of calmodulin in the pea plasma membrane. 249 18


1 2 3 4 5 6 Next >>

---