Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043167 (pertussis)
 19,595 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cortex of the rabbit (Oryctolagus cuniculus) is rich in melatonin binding sites, and particularly abundant is the parietal cortex. Consequently, we characterized the putative melatonin receptor in the parietal cortex by a series of in vitro ligand-receptor binding experiments and biochemical and electrophysiological studies. The in vitro saturation and competition experiments demonstrated that the binding in the crude cortical membrane preparations was of high affinity and specificity. Guanine nucleotides (GDP, GTP, and GTP gamma S) inhibited the specific 2-[125I]iodomelatonin binding in a dose-dependent manner. Coincubation with a nonhydrolyzable GTP analog provoked a shift in the binding affinity; the numerical values of the Kd increased from 20-30 to 200-600 pM. Melatonin, in nanomolar concentrations, was able to inhibit the forskolin-stimulated accumulation of cAMP in parietal cortex explants, and preincubation with pertussis toxin counteracted this effect of melatonin. Apparently, the melatonin binding site in the rabbit parietal cortex is linked to its second messenger via a pertussis toxin-sensitive G-protein, probably of the inhibitory Gi class, similar to what has been described for different parts of the brain of other vertebrates. The experiments on the spontaneous firing activity of single neurons in the third to fourth layer of the parietal cortex in anesthetized animals showed that melatonin and its potent agonist 2-iodomelatonin exhibited gamma-aminobutyric acid (GABA)-like effects and were able alone, in nanomolar concentrations, to significantly slow the neuronal firing activity. Moreover, both melatonin and 2-iodomelatonin potentiated the effect of GABA on the neuronal activity, leading to powerful inhibition of the tested neurons. Undoubtedly, the binding site in the rabbit parietal cortex possesses all of the characteristics of a functional receptor. We suggest that melatonin is involved in the control of fundamental cortical functions and that it acts in concert with GABA, one of the two major inhibitory neurotransmitters in the central nervous system.
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PMID:Melatonin signal transduction and mechanism of action in the central nervous system: using the rabbit cortex as a model. 131 48

Guanine nucleotide-, neurotransmitter-, and fluoride-stimulated accumulation of [3H]inositol phosphates ([3H]InsPs) was measured in [3H]inositol-labeled synaptoneurosomes from cerebral cortex of immature (7-day-old) and adult rats, in order to clarify the role of GTP-binding proteins (G-proteins) in modulating phosphoinositide (PtdIns) metabolism during brain development. GTP(S) [Guanosine 5'-O-(3-thio)triphosphate] time- and concentration-dependently stimulated PtdIns hydrolysis. Its effect was potentiated by full (carbachol, metacholine) and partial (oxotremorine) cholinergic agonists through activation of muscarinic receptors. The presence of deoxycholate was required to demonstrate agonist potentiation of the guanine nucleotide effect. The response to GTP(S) was higher in adult than in immature rats, while the effect of cholinergic agonists was similar at the two ages examined. At both ages, histamine potentiated the effect of GTP(S), while norepinephrine was ineffective. At both ages, guanosine 5'-O-(2-thio)diphosphate [GDP(S)] and pertussis toxin significantly decreased GTP(S)-induced [3H]InsPs formation. The phorbol ester phorbol 12-myristate 13-acetate (PMA), on the other hand, did not inhibit the guanine nucleotide response in synaptoneurosomes from immature rats. NaF mimicked the action of GTP(S) in stimulating PtdIns hydrolysis. Its effect was not affected by carbachol and was highly synergistic with that of AlCl3, according to the concept that fluoroaluminate (AlF4-) is the active stimulatory species. No quantitative differences were found in the response to these salts between immature and adult animals. These results provide evidence that, in both the immature and adult rat brain, neuroreceptor activation is coupled to PtdIns hydrolysis through modulatory G-proteins.
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PMID:Guanine nucleotide- and muscarinic agonist-dependent phosphoinositide metabolism in synaptoneurosomes from cerebral cortex of immature rats. 136 Oct 27

Guanine nucleotide-binding proteins (G proteins) mediate signals between serotonin receptors and adenylate cyclase in Schistosoma mansoni. A bovine Gs alpha cDNA probe was used to isolate a cDNA clone, SG12, encoding the entire alpha-subunit of a G protein of S. mansoni. The cDNA is 1897 base pairs long, contains an open reading frame of 1137 base pairs, and codes for a deduced protein of 379 amino acids. The putative protein encoded by the clone has an exact amino acid match with bovine Gs alpha of 65% and a 78% match when conserved amino acid substitutions are considered. In contrast, the exact and conserved matches of the schistosome alpha-subunit with bovine Gi are 41 and 61%, respectively. A comparison of the deduced amino acid sequence of SG12 with a variety of different G alpha proteins indicates that all the major structural features characteristic of a Gs alpha protein are present in the S. mansoni gene. The schistosome clone contains the putative site for ADP-ribosylation by cholera toxin found in Gs alpha but does not contain the ADP-ribosylation site for pertussis toxin present in Gi alpha. The amino acids are completely conserved at the GTP-binding sites. On a Northern blot, the cDNA hybridizes to a major band of 3.1 kilobases in RNA from adult schistosomes. The message appears to be absent in miracidia and cercariae, but a faint 3.1-kilobase band is visible in the early schistosomule stage preceding adulthood. This evidence, when added to previous biochemical data, indicates that the expression of this gene is developmentally controlled.
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PMID:Cloning and characterization of a cDNA coding for the alpha-subunit of a stimulatory G protein from Schistosoma mansoni. 137 44

The present studies were conducted to characterize the specific binding of recombinant human [125I]acidic fibroblast growth factor ([125]aFGF) to the cloned human fibroblast growth factor (FGF) receptor, flg, overexpressed on stably transfected NIH 3T3 mouse fibroblast (NFlg26) cell membranes. In the presence of 5 U/ml of heparin to block [125I]aFGF binding to membrane bound heparan sulfate proteoglycans, specific [125I]aFGF binding was optimal in the presence of 0.2 M NaCl and in a pH range of 7 to 9. [125I]aFGF labeled a single class of recognition sites with high affinity (Kd = 0.27 nM) and limited capacity (apparent maximum binding = 19.5 pmol/mg of protein). A similar estimate of ligand affinity (Kd = 0.25 nM) was determined from association and dissociation rate experiments. aFGF, basic fibroblast growth factor and several glycine-substituted point mutations of aFGF potently inhibited 0.1 nM [125I]aFGF binding. A variety of putative FGF receptor ligands including poly-L-lysines and poly-L-arginines, protamine, suramin and wheat germ agglutinin were shown to have weak or no affinity for the [125I]aFGF recognition site. Additional saturation studies, conducted in the presence of a lower (0.1 U/ml) heparin concentration, indicated that [125I] aFGF labeled both the high affinity (Kd = 0.02 nM) FGF-flg receptor and a separate class of lower affinity (Kd = 2 nM) recognition sites. Pretreatment of NFlg26 cell membranes with pertussis toxin resulted in a heparin-dependent decrease in the binding affinity (Kd values of 0.57-1.15 nM) of [125I]aFGF. Similar pretreatment with cholera toxin did not significantly affect [125I] aFGF binding. Guanine nucleotides were also found to significantly reduce 0.1 nM [125I]aFGF binding in a heparin-dependent fashion. The present data demonstrate that, in the presence of heparin, [125I]aFGF binds with high affinity to the cloned FGF-flg receptor on NFlg26 cell membranes. However, at a low heparin concentration (0.1 U/ml), [125I]aFGF binds to the FGF-flg receptor with higher affinity than was observed in the presence of 5 U/ml of heparin, and also binds a class of lower affinity recognition sites which are consistent with the labeling of cell surface heparan sulfate proteoglycans. The present data also indicate that agents which are known to interfere with receptor/G-protein coupling reduce the binding affinity of [125I]aFGF and suggest that the FGF-flg receptor may be coupled to a G-protein in addition to its intrinsic tyrosine kinase activity.
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PMID:Characterization of [125I]acidic fibroblast growth factor binding to the cloned human fibroblast growth factor receptor, FGF-flg, on NIH 3T3 cell membranes: inhibitory effects of heparin, pertussis toxin and guanine nucleotides. 138 94

Photoaffinity labelling by a GTP analogue has been used to identify a 42 kDa band as the major G alpha subunit in squid photoreceptor membranes, recently identified by partial sequence analysis to be a member of the Gq sub-group of GTP-binding proteins [Pottinger, Ryba, Keen & Findlay (1991) Biochem. J. 279, 323-326]. Guanine-nucleotide-binding displacement analysis gave a stoichiometry of 1 G-protein per 12.5 rhodopsin molecules, the same as in vertebrate rod photoreceptors. Binding was not detected above background in the dark, but was rapidly activated by light. Unlike vertebrate transducin, this G-protein is very temperature-sensitive. GTP binding is maximal at temperatures less than 10 degrees C and is much decreased after several minutes above 18 degrees C. The light-stimulated GTPase rate is maximal around 10 degrees C, above which the loss of binding sites counteracts the increase in hydrolytic rate per site. Earlier studies described light-sensitive G alpha components of 40 and 45 kDa, by ADP-ribosylation in the presence of cholera and pertussis toxins. These are now shown to be very minor components, as the prolonged treatment at elevated temperature required for ADP-ribosylation is sufficient to inactivate the major G alpha totally. Unlike the minor G alpha components, the 42 kDa G alpha is not inhibited by Ca2+.
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PMID:Activation of the GTP-binding protein Gq by rhodopsin in squid photoreceptors. 144 12

Guanine nucleotide-binding regulatory proteins play key intermediary roles in regulating zona pellucida-mediated acrosomal exocytosis in mouse and bull sperm. Since human sperm possess a Gi-like protein and undergo the acrosome reaction in response to the human zona pellucida, we investigated whether this G protein plays a regulatory role in this exocytotic process. Zonae pellucidae isolated from eggs that had been inseminated but had shown no signs of fertilization after retrieval for in vitro fertilization and embryo transfer were pooled into groups of greater than or equal to 50 in order to reduce variability in biological responses due to the possible presence of ZP that had undergone modifications associated with the polyspermy block. Acid-solubilized zonae pellucidae were incubated with capacitated sperm, and the sperm then assessed for the acrosome reaction using both the P. sativum agglutinin and chlortetracycline fluorescence assays; both assays gave similar results. Sperm incubated with solubilized zonae pellucidae at a final concentration of 2, 4, or 6 ZP/microliter underwent acrosomal exocytosis to a similar extent as compared with A-23187. Sperm were incubated with 1 microgram/ml pertussis toxin during capacitation to functionally inactivate the Gi-like protein. Pertussis toxin treatment of sperm did not affect sperm motility and the ability of the cells to bind to structurally intact zonae pellucidae. Pertussis toxin, however, completely inhibited the percentage acrosome reactions induced by solubilized zonae pellucidae. By contrast, the A-23187-induced acrosome reaction was insensitive to PT treatment. Pertussis toxin inhibition of the zona pellucida-induced acrosome reaction occurred in a concentration-dependent manner with maximal effects observed at 100 ng/ml PT.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A guanine nucleotide-binding regulatory protein in human sperm mediates acrosomal exocytosis induced by the human zona pellucida. 156 31

Guanine nucleotide binding (G) proteins play a pivotal role in postreceptor information transduction. An important characteristic of G proteins is their increased guanine nucleotide binding following agonist stimulation, which in turn leads to their activation. We have developed a method that enables the measurement of early events in signal transduction beyond receptors, through activated receptor-coupled guanine nucleotide exchange on G proteins. Using this method, lithium was recently demonstrated to inhibit the coupling of both muscarinic cholinergic and beta-adrenergic receptors to pertussis toxin-sensitive and cholera toxin-sensitive G proteins, respectively, thus suggesting alteration of the function of G protein by lithium, as the single site for both the antimanic and antidepressant effects of this drug. One of the most puzzling aspects of the ability of lithium to ameliorate the manic-depressive condition is its relatively selective action upon the central nervous system (CNS). It was previously shown that lithium selectively attenuated the function of Gs proteins in the CNS. In the present study, we show that inhibition by lithium of muscarinic receptor-coupled G protein function is also selective to the CNS. The clinical profile of lithium, carbamazepine, and electroconvulsive treatment (ECT), agents that are effective in the prevention and treatment of bipolar affective disorder, differs from that of purely antidepressant drugs. Antidepressant drugs are effective in the acute treatment and prevention of depression only, and can even precipitate hypomanic or manic "switches," or "rapid cycling" between mania and depression. We have investigated and compared the effects of chronic antibipolar and antidepressant treatments on receptor-coupled G protein function. Antibipolar treatments (lithium, carbamazepine, ECT) attenuate both receptor-coupled Gs and non-Gs (i.e., Gi, Go) proteins function; in contrast, only Gs protein function is inhibited by antidepressant drugs [either tricyclics or monoamine oxidase (MAO) inhibitors]. Moreover, an integral adrenergic neuronal system is required for antidepressant inhibition of Gs protein function, as pretreatment with the noradrenergic neurotoxin DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine) specifically abolishes the effects of antidepressant drugs on Gs protein, whereas antibipolar drug effects on G protein function are unaffected by DSP-4. Our results suggest that attenuation of beta-adrenergic receptor-coupled Gs protein function, which is common to both antidepressant and antibipolar treatments, may be the mechanism underlying their antidepressant therapeutic efficacy.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Ziskind-Somerfeld research Award. The involvement of guanine nucleotide binding proteins in the pathogenesis and treatment of affective disorders. 158 23

Differentiated HL-60 granulocytes were used to study the mechanism by which tumour necrosis factor-alpha (TNF) enhances responses to N-formyl-methionyl-leucylphenylalanine (FMLP). Cultivation of differentiated HL-60 cells with 100 units of TNF/ml for 24 h resulted in a 3-fold increase in superoxide release and 4-fold increase in prostaglandin E2 production on stimulation with 1 microM-FMLP. On the other hand, cultivation with TNF failed to increase phorbol diester stimulation of superoxide release. Formyl-peptide-receptor expression determined on isolated membranes from cells cultivated with TNF (TNF-M) was increased by 50% compared with membranes from control cells (NM). Similarly, FMLP binding to intact HL-60 cells was increased by cultivation with TNF. Guanine-nucleotide-binding proteins (G-protein) levels were not different between TNF-M and NM, as determined by pertussis-toxin-catalysed ADP-ribosylation and by immunoblotting with antisera recognizing alpha i2 subunit. Binding of guanosine 5'-[gamma-thio]triphosphate and GTP hydrolysis stimulated by FMLP were enhanced by about 50% in TNF-M. The efficiency of G-protein activation by formyl-peptide receptors did not differ between TNF-M and NM. TNF regulates expression of formyl-peptide receptors independently of G-protein levels. The regulation of receptor expression is one mechanism by which TNF enhances cell responses to formylated peptides.
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PMID:Modulation of transmembrane signalling in HL-60 granulocytes by tumour necrosis factor-alpha. 165 80

Guanine nucleotide-binding proteins (G proteins) transduce signals from agonist- and light-sensitive receptors. In the visual excitation system, the photon receptor rhodopsin is coupled to the G protein Gt (transducin). Gt is composed of alpha, beta, and gamma subunits; the alpha subunit binds guanine nucleotide, whereas the beta and gamma subunits, which are tightly associated, appear to facilitate interaction of alpha with receptor and pertussis toxin-catalyzed ADP-ribosylation of alpha. To study the function of transducin, monoclonal antibodies were developed against the purified protein. Monoclonal antibody 2H3 reacted with Gt gamma but not G gamma from bovine brain or rabbit liver. In the absence of photolyzed rhodopsin, both intact 2H3 and Fab fragments of 2H3 were able to inhibit completely, in a concentration-dependent manner, ADP-ribosylation of transducin by pertussis toxin 2H3 had no effect on ADP-ribosylation in the presence of photolyzed rhodopsin. The GTPase activity of transducin, which is dependent on rhodopsin, was inhibited only 50% by 2H3. These data are consistent with the hypotheses that an epitope recognized by 2H3 may be important in the formation of the alpha beta gamma complex or that interaction of 2H3 with gamma may alter conformation of the latter and, thereby, inhibit complex formation. Further, reactions of gamma with 2H3 appear to be prevented by interaction with rhodopsin, suggesting that its interaction either shields or alters the epitope recognized by 2H3.
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PMID:Immunological characterization of guanine nucleotide-binding proteins: effects of a monoclonal antibody against the gamma subunit of transducin on guanine nucleotide-binding protein-receptor interactions. 169 60

Guanine nucleotide-binding proteins (G proteins) are key components in membrane signal transduction that may play an important role in testis function. The present study is the first description of cell-specific differences in the contents of G protein alpha-subunits and their mRNAs in isolated rat testicular cells (pachytene spermatocytes, round spermatids, Sertoli cells, peritubular cells). By using Western blot techniques G1-3 alpha was shown to be the only pertussis toxin (PTX) substrate present in all the testicular cells examined. Surprisingly, we observed a lack of immunoreactive Gi-1 alpha/Gi-2 alpha protein in pachytene spermatocytes and round spermatids in spite of significant levels of the corresponding mRNAs as revealed by Northern analysis. No immunoreactive Gs alpha was detected in germ cells, in agreement with previous findings that the hormone-sensitive adenylyl cyclase is absent in these cell types. Peritubular cells and Sertoli cells contained no Go alpha, whereas high levels of both immunoreactive protein and mRNA were found in pachytene spermatocytes. This indicates that the Go protein may play a role at this stage of spermatogenesis. The stimulation of phospholipase C (PLC) in germ cell membranes by 5'-guanylyl imidophosphate indicates that PTX-sensitive PLC activation may be mediated by Go alpha or Gi-3 alpha.
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PMID:Cell-specific expression of guanine nucleotide-binding proteins in rat testicular cells. 175 30


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