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

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

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

Intracellular recordings were made from rat dorsal horn neurons in the in vitro slice preparation to study the actions of cyclic adenosine 3',5'-monophosphate (cyclic AMP). In the presence of TTX, bath application of the membrane permeable analogue of cyclic AMP, 8-Br cyclic AMP (25-100 microM) caused a small depolarization of the resting membrane potential accompanied by a variable change in membrane input resistance. In addition, 8-Br cyclic AMP caused a long-lasting increase in the spontaneous synaptic activity and the amplitude of presumed monosynaptic excitatory postsynaptic potentials evoked in the substantia gelatinosa neurons by orthodromic stimulation of a lumbar dorsal root. When the fast voltage-sensitive Na conductance was blocked by TTX, 8-Br cyclic AMP enhanced in a reversible manner, the depolarizing responses of a proportion of dorsal horn neurons to N-methyl-D-aspartic acid (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), quisqualic acid (QA) and kainic acid (KA). The effects of 8-Br cyclic AMP on the resting membrane potential and the NMDA response of dorsal horn neurons were mimicked by reducing phosphodiesterase activity with bath application of 3-isobutyl-1-methylxanthine, but not by cyclic AMP applied extracellularly. Moreover, we have found that intracellular application of a protein inhibitor of cyclic AMP-dependent protein kinase (PKI) into dorsal horn neurons prevents the 8-Br cyclic AMP-induced potentiation of the NMDA response of these cells. These results suggest that in the rat spinal dorsal horn the activation of the adenylate cyclase-cyclic AMP-dependent protein kinase system may be involved in the enhancement of the sensitivity of postsynaptic excitatory amino acid (NMDA, AMPA, KA) receptors and modulation of primary afferent neurotransmission, including nociception.
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PMID:Cyclic adenosine 3'5'-monophosphate potentiates excitatory amino acid and synaptic responses of rat spinal dorsal horn neurons. 133 73

Ca2+-dependent cyclic nucleotide phosphodiesterase (Ca2+-PDE) activity was stimulated by poly(L-aspartic acid) but not by poly(L-glutamic acid), poly(L-arginine), poly(L-lysine), and poly(L-proline). This activation was Ca2+ independent and did not further enhance the activation of Ca2+-PDE by Ca2+-calmodulin (CaM). Poly(L-aspartic acid) produced an increase in the Vmax of the phosphodiesterase, associated with a decrease in the apparent Km for the substrate, such being similar to results obtained with Ca2+-CaM. Poly(L-aspartic acid) did not significantly stimulate myosin light chain kinase and other types of cyclic nucleotide phosphodiesterase. CaM antagonists such as N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), trifluoperazine, and chlorpromazine selectively antagonized activation of the enzyme by poly(L-aspartic acid). Kinetic analysis of W-7-induced inhibition of activation of phosphodiesterase by poly(L-aspartic acid) was in a competitive fashion, and the Ki value was 0.19 mM. On the other hand, prenylamine, another type of calmodulin antagonist that binds to CaM at sites different from the W-7 binding sites, did not inhibit the poly(L-aspartic acid)-induced activation of Ca2+-dependent cyclic nucleotide phosphodiesterase. These results imply that poly(L-aspartic acid) is a calcium-independent activator of Ca2+-dependent phosphodiesterase and that aspartic acids in the CaM molecule may play an important role in the activation of Ca2+-PDE.
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PMID:Ca2+-dependent cyclic nucleotide phosphodiesterase is activated by poly(L-aspartic acid). 300 Apr 29

Acylpeptides, APD-I, -II and -III, were inhibitors of cyclic adenosine 3',5'-monophosphate (cAMP) phosphodiesterase, and their inhibition types were non-competitive. The inhibitory activity of APD-II was the most potent among them. Opening of the lactone linkage reduced the inhibitory activity to about half. The activity almost disappeared when an inhibitor or a derivative with opened lactone linkage was methylated with diazomethane. The activity was, however, restored by the addition of metal ions such as Ca2+, Mn2+, Fe2+, and Co2+. This suggests that the inhibition may be caused by a chelating action of the free carboxyl groups of glutamic acid and aspartic acid in the peptide.
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PMID:Acylpeptides, the inhibitors of cyclic adenosine 3',5'-monophosphate phosphodiesterase. III. Inhibition of cyclic AMP phosphodiesterase. 630 59

Inzolen, a combination of the potassium, magnesium, copper, manganese and cobalt salts of aspartic acid, inhibits the second phase of ADP-induced aggregation probably by affecting the membrane-located adenylatecyclase/phosphodiesterase system. Correspondingly inzolen affects the activation of platelet factor 3 (PF3), which is also located in the platelet membrane. Thus spontaneous as well as kaolin-induced platelet factor availability is reduced by inzolen. The significant inhibition of factor 3 availability can be interpreted by a magnesium-mediated activation of phosphoryltransferases.
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PMID:[Potassium, magnesium, copper, manganese and cobalt salts of aspartic acid on platelet factor 3 availability (author's transl)]. 719 69

General anesthetics, including halothane, isoflurane, and barbiturates, suppress endothelium-dependent formation of 3',5'-cyclic guanosine monophosphate (cGMP) in the systemic and cerebral vasculature. The present study was conducted to determine whether these anesthetics have similar effects on the nitric oxide (NO)-cGMP system in the brain, and to elucidate the mechanism responsible. In rat cerebellar slices, formation of cGMP was suppressed by halothane after stimulation by N-methyl-D-aspartate (NMDA, 0.1 mM) and D-aspartate (1.0 mM) but not after stimulation by sodium nitroprusside (SNP, 0.3 mM). Isoflurane (2%) suppressed NMDA (0.1 mM)-stimulated, but not D-aspartate (1.0 mM)- and nitroprusside (0.3 mM)-stimulated formation of cGMP. In contrast, thiopental (0.1-1.0 mM) suppressed NMDA (0.1 mM)-, D-aspartate (1.0 mM)-, and nitroprusside (0.3 mM)-stimulated formation of cGMP. Treatment with aminophylline (0.1 mM), a phosphodiesterase inhibitor, did not influence the effect of thiopental, suggesting that the effect of thiopental was not mediated by activation of phosphodiesterase. D-Aspartate increases intracellular calcium, which in turn activates NO synthase, and nitroprusside generates NO without activation of NO synthase. Therefore, the present findings strongly suggest that halothane inactivates NO synthase (or related cofactors) without marked interaction with the NMDA receptor, that isoflurane may interact with the NMDA receptor, receptor-coupled G-protein, or calcium channels, and that thiopental suppresses guanylate cyclase activity.
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PMID:Inhibitory effects of anesthetics on cyclic guanosine monophosphate (cGMP) accumulation in rat cerebellar slices. 752 47

The amino acid sequences of all known cGMP-binding phosphodiesterases (PDEs) contain internally homologous repeats (a and b) that are 80-90 residues in length and are arranged in tandem within the putative cGMP-binding domains. In the bovine lung cGMP-binding, cGMP-specific PDE (cGB-PDE or PDE5A), these repeats span residues 228-311 (a) and 410-500 (b). An aspartic acid (residue 289 or 478) that is invariant in repeats a and b of all known cGMP-binding PDEs was changed to alanine by site-directed mutagenesis of cGB-PDE, and wild type (WT) and mutant cGB-PDEs were expressed in COS-7 cells. Purified bovine lung cGB-PDE (native) and WT cGB-PDE displayed identical cGMP-binding kinetics, with approximately 1.8 microM cGMP required for half-maximal saturation. The D289A mutant showed decreased affinity for cGMP (Kd > 10 microM) and the D478A mutant showed increased affinity for cGMP (Kd approximately 0.5 microM) as compared to WT and native cGB-PDE. WT and native cGB-PDE displayed an identical curvilinear profile of cGMP dissociation which was consistent with the presence of distinct slowly dissociating (koff = 0.26 h-1) and rapidly dissociating (koff = 1.00 h-1) sites of cGMP binding. In contrast, the D289A mutant displayed a single koff = 1.24 h-1, which was similar to the calculated koff for the fast site of WT and native cGB-PDE, and the D478A mutant displayed a single koff = 0.29 h-1, which was similar to that calculated for the slow site of WT and native cGB-PDE. These results were consistent with the loss of a slow cGMP-binding site in repeat a of the D289A mutant cGB-PDE, and the loss of a fast site in repeat b of the D478A mutant, suggesting that cGB-PDE possesses two distinct cGMP-binding sites located at repeats a and b, with the invariant aspartic acid being crucial for interaction with cGMP at each site.
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PMID:An essential aspartic acid at each of two allosteric cGMP-binding sites of a cGMP-specific phosphodiesterase. 853 May 5

Comparisons of the tertiary structures of the GDP-bound and guanosine 5'-O-(thiotriphosphate) (GTPgammaS)-bound forms of the alpha subunit of transducin (alphaT) indicate that there are three regions that undergo changes in conformation upon alphaT activation. Two of these regions, Switch I and Switch II, were originally identified in Ras, while Switch III appears to be unique to trimeric GTP-binding proteins (G proteins). We find that replacement of the Switch III region (aspartic acid 227 through asparagine 237) with a single alanine residue yields an alphaT subunit that fully binds and hydrolyzes GTP but no longer stimulates the activity of the cyclic GMP phosphodiesterase (PDE), the physiological target for transducin. We also show that changing glutamic acid 232 of alphaT to a leucine (E232L) had no effect on rhodopsin-stimulated GTP-GDP exchange nor on the GTP hydrolytic activity of alphaT. However, the GTPgammaS-bound form of the alphaTE232L mutant was unable to stimulate the activity of the cyclic GMP PDE. The lack of stimulation was not due to an inability of the alphaTE232L mutant to bind to the target. Taken together, these results indicate that glutamic acid 232 mediates a conformational coupling between Switch II and Switch III, which is essential for converting GTP-dependent G protein-target interactions into a stimulation of target/effector activity.
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PMID:Communication between switch II and switch III of the transducin alpha subunit is essential for target activation. 926 92

The biological roles of nitric oxide (NO) and cGMP as inter- and intracellular messengers have been intensively investigated during the last decade. NO and cGMP both mediate physiological effects in the cardiovascular, endocrinological, and immunological systems as well as in central nervous system (CNS). In the CNS, activation of the N-methyl-D-aspartic acid (NMDA) type of glutamatergic receptor induces Ca(2+)-dependent NOS and NO release, which then activates soluble guanylate cyclase for the synthesis of cGMP. Both compounds appear to be important mediators in long-term potentiation and long-term depression, and thus may play important roles in the mechanisms of learning and memory. Aging and the accumulation of amyloid beta (A beta) peptides are important risk factors for the impairment of memory and development of dementia. In these studies, the mechanism of basal- and NMDA receptor-mediated cGMP formation in different parts of adult and aged brains was evaluated. The relative activity of the NO cascade was determined by assay of NOS and guanylate cyclase activities. In addition, the effect of the neurotoxic fragment 25-35 of A beta (A beta) peptide on basal and NMDA receptor-mediated NOS activity was investigated. The studies were carried out using slices of hippocampus, brain cortex, and cerebellum from 3- and 28-mo-old rats. Aging coincided with a decrease in the basal level of cGMP as a consequence of a more active degradation of cGMP by a phosphodiesterase in the aged brain as compared to the adult brain. Moreover, a loss of the NMDA receptor-stimulated enhancement of the cGMP level determined in the presence of cGMP-phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) was observed in hippocampus and cerebellum of aged rats. However, this NMDA receptor response was preserved in aged brain cerebral cortex. A significant enhancement of the basal activity of NOS by about 175 and 160% in hippocampus and cerebellum, respectively, of aged brain may be involved in the alteration of the NMDA receptor response. The neurotoxic fragment of A beta, peptide 25-35, decreased significantly the NMDA receptor-mediated calcium, and calmodulim-dependent NO synthesis that may then be responsible for disturbances of the NO and cGMP signaling pathway. We concluded that cGMP-dependent signal transduction in hippocampus and cerebellum may become insufficient in senescent brain and may have functional consequences in disturbances of learning and memory processes. A beta peptide accumulated during brain aging and in Alzheimer disease may be an important factor in decreasing the NO-dependent signal transduction mediated by NMDA receptors.
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PMID:Aging modulates nitric oxide synthesis and cGMP levels in hippocampus and cerebellum. Effects of amyloid beta peptide. 1034 72

To elucidate the physiological significance of the translocation of Ca(2+)/calmodulin-dependent protein kinase II (CaM kinase II), we investigated substrates of CaM kinase II in the postsynaptic density (PSD). PSD proteins were phosphorylated by CaM kinase II of its PSD complex, and separated by two-dimensional gel electrophoresis. More than 28 proteins were phosphorylated under experimental conditions. Proteins corresponding to CaM kinase II substrates were excised from the gels, eluted electrophoretically, and then sequenced. Several substrates were identified, including PSD95, SAP90, alpha-internexin, neurofilament L chain, cAMP phosphodiesterase, and alpha- and beta-tubulin. Some substrates were also identified by immunoblotting, including N-methyl-D-aspartic acid (NMDA) receptor 2B subunit, 1-alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor 1 (GluR1), neurofilament H chain and dynamin. PSD95, SAP90, dynamin, and alpha-internexin were demonstrated for the first time to be substrates of CaM kinase II. NMDA receptor 2B subunit and GluR1 existed as major substrates in the PSD. Moreover, translocation of CaM kinase II was inhibited by phosphorylation of PSD proteins. These results suggest that CaM kinase II plays important roles in the regulation of synaptic functions through phosphorylation of PSD proteins.
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PMID:Investigation of protein substrates of Ca(2+)/calmodulin-dependent protein kinase II translocated to the postsynaptic density. 1100 Apr 84


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