Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To investigate the role of guanosine 3':5'-monophosphate (cyclic GMP) in cultured cells we have measured guanylate cyclase and cyclic GMP phosphodiesterase activities and cyclic GMP levels in normal and transformed fibroblastic cells. Guanylate cyclase activity is found almost exclusively in the particulate fraction of normal rat kidney (NRK) and BALB 3T3 cells. Enzyme activity is stimulated 3- to 10-fold by treatment with the detergent Lubrol PX. However, enhancement of guanylate cyclase by fibroblast growth factor could not be demonstrated under a variety of assay conditions. In both NRK and BALB 3T3 cells guanylate cyclase activity is low during logarithmic growth and increases as the cells crowd together and growth slows. Guanylate cyclase activity is undetectable in homogenates of NRK cells transformed by the Kirsten sarcoma virus (KNRK cells) either in the presence or absence of Lubrol PX. Guanylate cyclase activity is also greatly decreased in NRK cells transformed by Moloney, Schmidt-Ruppin, or Harvey viruses. BALB 3T3 cells transformed by RNA viruses (Kirsten, Harvey, or Moloney), by a DNA virus (SV40), by methylcholanthrene, or spontaneously, all have diminished but readily detectable guanylate cyclase activity. Cyclic GMP phosphodiesterase activity is found predominately in the soluble fraction of NRK cells. This activity increases slightly as NRK cells enter the stationary growth phase. Cyclic GMP phosphodiesterase activity is undetectable in two clones of KNRK cells under a variety of assay conditions, and is decreased relative to the level present in NRK cells in a third KNRK clone. However, both Moloney- and Schmidt-Ruppin-transformed NRK cells have a phosphodiesterase activity similar to that found in NRK cells. Boiled supernatant from both NRK and KNRK cells is observed to appreciably enhance the activity of activator-deficient phosphodiesterase from bovine heart. This result indicates that the absence of cyclic GMP phosphodiesterase activity in KNRK cells is not due to a loss of the phosphodiesterase activator. The intracellular concentration of cyclic GMP is found to be very low in transformed NRK cells when compared to levels measured in confluent NRK cells. The low levels of cyclic GMP in transformed NRK cells reflect the greatly decreased guanylate cyclase activity observed in these cells. These results do not appear to support the suggestion that cyclic GMP promotes the growth of fibroblastic cells.
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PMID:Guanylate cyclase and cyclic guanosine 3':5'-monophosphate phosphodiesterase activities and cyclic guanosine 3':5'-monophosphate levels in normal and transformed fibroblasts in culture. 0 44

An acidic, low molecular weight (18 400--19 100) protein capable of activating porcine brain phosphodiesterase in the presence of calcium has been purified 2700-fold from the anthozoan coelenterate, Renilla reniformis. The protein has physical, spectral, and chemical properties similar to those of modulator proteins isolated from mammalian species. Amino acid composition studies reveal no significant differences between the Renilla and mammalian modulator proteins. For example, we observed 1 mol of epsilon-N-trimethyllysine per mol of protein, no tryptophan or cysteine, and high levels of glutamic and aspartic acid residues. The protein from Renilla complexes with troponin I and T subunits in the presence of calcium and quantitatively replaces porcine brain modulator in the calcium-dependent activation of porcine brain phosphodiesterase. The protein has a high affinity for calcium as judged by the low levels of free calcium required for modulator-dependent activation of phosphodiesterase. The similarities in physical and chemical properties, high affinity for calcium, and identical calcium-dependent activities of this protein from Renilla (as compared with modulator protein purified from mammalian systems) suggest that a high degree of structural conservation has been retained in modulator proteins isolated from these diverse evolutionary forms.
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PMID:Isolation and characterization of Ca2+-dependent modulator protein from the marine invertebrate Renilla reniformis. 3 94

The possible relationship between phosphatidyl serine synthesis by base-exchange and nervous activity has been investigated in the rat caudate nucleus. The rate of incorporation of L-serine into the phosphatidyl serine of slices from caudate nucleus is not affected by dopamine nor is it affected by the addition to dopamine of a cyclic phosphodiesterase inhibitor which would increase the endogenous cyclic-AMP levels. However, imidazole, a phosphodiesterase activator, clearly stimulates by more than 100% the phosphatidyl serine synthesis in the slices. The activation is not due to interaction at the catalytic site(s) of the base-exchange system, since it is neither observed in homogenates of caudate nucleus nor in cerebral microsomes at various pH values.
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PMID:Activation of phosphatidylserine synthesis: a possible mechanism of regulation of the base-exchange enzymic system. 4 72

Active transport of calcium into inside-out vesicles of red blood cell membranes was stimulated equally by (i) the purified protein activator of calcium-activated, magnesium-dependent adenosinetriphosphatase isolated from red cell hemolyzates and (ii) calmodulin, a protein activator of cylic nucleotide phosphodiesterase isolated from bovine brain. The results provide further evidence for the identity of red blood cell activator and calmodulin and show that this cytoplasmic protein may participate in the regulation of plasma membrane calcium transport.
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PMID:Calcium transport across the plasma membrane: stimulation by calmodulin. 15 9

The brain as well as other mammalian tissues contains several different forms of cyclic nucleotide phosphodiesterase separable by polyacrylamide gel electrophoresis. Each tissue and each individual type of cell has its own distinctive pattern and ratio of these multiple forms of phosphodiesterase. The different forms have several distinguishing properties and characteristics, and their activities may be differentially regulated both acutely and chronically. The enzyme forms have different stabilities, kinetic properties, substrate specificities, and sensitivities to an endogenous activator and to several inhibitors of phosphodiesterase. The phosphodiesterase inhibitors studied not only inhibit the different forms of phosphodiesterase to different degrees but apparently do so by different mechanisms. Thus whereas theophylline, cyclic GMP, and low concentrations of papaverine inhibit the phosphodiesterases by competing with the substrate (cyclic AMP), trifluoperazine apparently inhibits phosphodiesterase by interfering with the phosphodiesterase activator. This confers a great deal of specificity to this drug, since only one form of phosphodiesterase is markedly activated by the activator. Chronically, a specific form of phosphodiesterase appears to be inducible. This induction is probably controlled by the intracellular cyclic AMP concentration. The phosphodiesterase activator also appears to be regulatable, the age of the animal being one of the factors controlling its activity. Finally, since different types of cells have different relative amounts of the phosphodiesterases and since these forms of the enzyme can be differentially inhibited by drugs, it may be possible to develop drugs which will selectively increase the cyclic AMP concentration in discrete cell types. Evidence that cyclic AMP is involved in certain disease states suggests further that by selectively altering the concentration of cyclic AMP in these cells, one might be able to alter the course of the disease.
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PMID:Differential activation and inhibition of the multiple forms of cyclic nucleotide phosphodiesterase. 16 66

The effect of the endogenous protein activator on the kinetic characteristics of a highly purified, activator-deficient rat brain phosphodiesterase (EC 3.1.4.-) of a highly purified, activator-deficient rat brain phosphodiesterase (EC 3.1.4-) was studied. This enzyme preparation has only a high Km for cyclic AMP and a low Km for cyclic GMP. In the presence of 20 muM Ca2+, saturating concentrations of the activator decreased the Km of this enzyme for cyclic AMP from 350 muM to about 80 muM, without changing the V. The phosphodiesterase activator did not change the Km of phosphodiesterase for cyclic GMP; however, amoderate increase of V was seen. The activator lacks species specificity; the activator isolated from the bullfrog sympathetic chain produced the same qualitative and comparable quantitative changes in the kinetic properties of the purified rat brain phosphodiesterase. Cyclic GMP is a potent competitive inhibitor of the phosphodiesterase activation by the activator (Ki=1.8 muM), using cyclic AMP as a substrate. Cyclic AMP inhibits slightly the hydrolysis of cyclic GMP by phosphodiesterase in the presence of activator (Ki=155 muM) only.
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PMID:A kinetic analysis of the cyclic nucleotide phosphodiesterase regulation by the endogenous protein activator. A study of rat brain and frog sympathetic chain. 17 44

In previous studies we have shown that the activation of bovine heart cyclic nucleotide phosphodiesterase by purified protein activator is completely dependent on the presence of Ca2+ and that the protein activator Ca2+ complex is probably the true activator for the enzyme (Teo, T.S. and Wang, J.H. (1973) J. Biol. Chem. 248, 5930-5955). More recent studies have led us to believe that the mechanism of the Ca2+ activation of phosphodiesterase resembles that of the Ca2+ activation of muscle contraction and that the protein activator may play a role similar to troponin. In the present study we show that the protein activator resembles rabbit muscle troponin C in amino acid composition, molecular weight, isoelectric point, and ultraviolet absorption spectrum. Preliminary structural studies also indicate that these two proteins may have evolved from a common ancestral protein through gene duplication. This argument is strengthened by the finding that the tryptic peptide map of the bovine heart protein activator is indistinguishable from that of the bovine brain phosphodiesterase activator protein for which preliminary sequence information also suggests homology to troponin C (Watterson, D.M., Harrelson, W.G., Jr., Keller, P.M., Sharief, F., and Vanaman, T.C. (1976) J. Biol. Chem. 251, 4501-4513).
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PMID:Comparison of calcium-binding proteins. Bovine heart and brain protein activators of cyclic nucleotide phosphodiesterase and rabbit skeletal muscle troponin C. 18 74

The concentration of a calcium-binding protein modulator of 3':5'-cyclic-nucleotide phosphodiesterase (EC 3.1.4.17; 3':5'-cyclic-nucleotide 5'-nucleotidohydrolase) activity is increased in chicken embryo fibroblasts upon transformation by Rous sarcoma virus. This modulator protein from fibroblasts, which has roughly the same molecular size, charge, and functional properties as that isolated from chicken brain, comprises approximately 1.32% of the soluble protein in homogenates of fibroblasts infected and transformed by Rous sarcoma virus. In comparison, the modulator comprises approximately 0.30% of the soluble protein in homogenates of normal fibroblasts from confluent cultures and 0.36% of the soluble protein in homogenates of fibroblasts infected with a transformation-defective mutant of Rous sarcoma virus. Modulator levels in normal fibroblasts at subconfluent cell densities are 0.42-0.76% of the homogenate soluble protein, i.e., between that found in confluent normal fibroblasts and in fibroblasts transformed by Rous sarcoma virus. These observations suggest that the levels of the modulator protein are elevated under conditions in which chicken embryo fibroblasts are undergoing rapid growth and have decreased adenosine 3':5'-cyclic monophosphate levels.
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PMID:Calcium-dependent regulatory protein of cyclic nucleotide metabolism in normal and transformed chicken embryo fibroblasts. 18 6

Measurements were made of the effectiveness of phosphodiesterase activator protein isolated from the cerebral cortex of rats of various ages in stimulating the phosphodiesterase-catalyzed conversion of cyclic-AMP into 5'-AMP. An age dependent increase in the potency of preparations of activator protein was observed, with the activator isolated from animals six months of age and older being generally more efficacious than that from younger animals.
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PMID:An effect of age on the phosphodiesterase activator protein of rat cerebral cortex. A brief note. 18 41

In order to test the hypothesis that the activity of cardiovascular centres is determined by their content of cAMP a number of drugs which influence the activity of either phosphodiestase or adenylcyclase were injected in doses of 100-1000 mug/kg into the lateral cerebral ventricle of cats. The effects on blood pressure and heart rate were studied. The phosphodiesterase inhibitors papaverine, carbocromene, theophylline and caffeine caused hypertension and tachycardia which increased with the dose while the phosphodiesterase activator imidazole exerted opposite effects. Sodium fluoride which activates adenylcyclase increased blood pressure and heart rate substantially. The results confirm the above-mentioned hypothesis.
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PMID:Further evidence for the involvement of cAMP in central blood pressure regulation. 18 30


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