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

Hepatocytes contain the Gi2 and Gi3 forms of the 'Gi-family' of guanine-nucleotide-binding proteins (G-proteins), but not Gi1. The anti-peptide antisera AS7 and I3B were shown to immunoprecipitate Gi2 and Gi3 selectively, and the antiserum CS1 immunoprecipitated the stimulatory G-protein Gs. Treatment of intact, 32P-labelled hepatocytes with one of glucagon, TH-glucagon ([1-N-alpha-trinitrophenylhistidine, 12-homoarginine]glucagon), Arg-vasopressin, angiotensin-II, the phorbol ester TPA (12-O-tetradecanoylphorbol 13-acetate) and 8-bromo-cyclic AMP elicited a time- and dose-dependent increase in the labelling of the alpha-subunit of immunoprecipitated Gi2 which paralleled the loss of ability of low concentrations of the non-hydrolysable GTP analogue guanosine 5'-[beta gamma-imido]triphosphate (p[NH]ppG) to inhibit forskolin-stimulated adenylate cyclase activity ('Gi'-function). The immunoprecipitation of phosphorylated Gi-2 alpha-subunit by the antiserum AS7 was blocked in a dose-dependent fashion by the inclusion of the C-terminal decapeptide of transducin, but not that of Gz (a 'Gi-like' G-protein which lacks the C-terminal cysteine group which is ADP-ribosylated by pertussis toxin in other members of the Gi family), in the immunoprecipitation assay. No labelling of the alpha-subunits of either Gi3 or Gs was observed. alpha-Gi2 was labelled in the basal state and this did not change over 15 min in the absence of ligand addition. In contrast to the monophasic dose-effect curves seen with vasopressin, angiotensin and TPA, the dose-effect curve for the glucagon-mediated increase in the labelling of alpha-Gi2 was markedly biphasic where the loss of Gi function paralleled the high-affinity component of the labelling of alpha-Gi2 caused by glucagon. TPA, TH-glucagon, angiotensin-II and vasopressin achieved similar maximal increases in the labelling of alpha-Gi2, which was approximately half that found after treatment of hepatocytes with either high glucagon concentrations (1 microM) or 8-bromocyclic AMP. Analysis of the phosphoamino acid content of immunoprecipitated alpha-Gi2 showed the presence of phosphoserine only. Incubation of hepatocyte membranes with [gamma-32P]ATP and purified protein kinase C, but not protein kinase A, led to the incorporation of label into immunoprecipitated alpha-Gi2. This labelling was abolished if membranes were obtained from cells which had received prior treatment with ligands shown to cause the phosphorylation of alpha-Gi2 in intact cells. We suggest that there are two possible sites for the phosphorylation of alpha-Gi2; one for C-kinase and the other for an unidentified kinase whose action is triggered by A-kinase activation.
 ...
PMID:Hormonal regulation of Gi2 alpha-subunit phosphorylation in intact hepatocytes. 211 93

A mechanism by which protein kinase C potentiates arachidonic acid (AA) liberation in rabbit platelets was examined using [3H]AA-labeled, saponin (7 micrograms/ml)-permeabilized rabbit platelets. Pretreatment of the [3H]AA-labeled platelets with 4 beta-phorbol 12-myristate 13-acetate (PMA, 10-40 nM) or 1,2-dioctanoylglycerol (DOG, 20 microM) enhanced [3H]AA liberation induced by an addition of Ca2+ (1 mM) after cell permeabilization, whereas 4 alpha-phorbol 12,13-didecanoate (80 nM) did not exert such an effect. The potentiating effects of PMA and DOG were inhibited by staurosporine (200 nM). PMA (40 nM) also potentiated [3H]AA liberation induced by guanosine 5'-[gamma-thio]triphosphate (GTP gamma S, 100 microM), 5'-guanylyl imidodiphosphate (200 microM) or NaF (20 mM) plus AlCl3 (10 microM) in the presence of Ca2+ (100 microM). The enhancement by PMA of the GTP gamma S-induced AA liberation was also inhibited by staurosporine (200 nM). Furthermore, guanosine 5'-[beta-thio]diphosphate (GDP beta S, 0.5-2 mM) suppressed the PMA (40 nM)- and DOG (20 microM)-enhanced, Ca2+ (1 mM)-dependent [3H]AA liberation. This inhibitory effect of GDP beta S was reversed by a further addition of GTP gamma S (200 microM). However, pertussis toxin (0.2-1 micrograms/ml) had no effect on the PMA-enhanced [3H]AA liberation. These results indicate a possibility that protein kinase C may potentiate AA liberation through a guanine-nucleotide-binding protein-mediated mechanism in saponin-permeabilized rabbit platelets.
 ...
PMID:Involvement of a guanine-nucleotide-binding protein-mediated mechanism in the enhancement of arachidonic acid liberation by phorbol 12-myristate 13-acetate and Ca2+ in saponin-permeabilized platelets. 211 77

The effect of the hydrolysis-resistant GTP analogs, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and guanylyl imidodiphosphate (GMPPNP), on norepinephrine (NE) secretion from digitonin-permeabilized rat pheochromocytoma cells, PC12, was examined. Although secretion in the presence of saturating Ca2+ (10 microM) was not affected by GTP gamma S or GMPPNP, secretion in the absence of Ca2+ was stimulated by these GTP analogs. Secretion induced by saturating concentrations of GTP gamma S or GMPPNP was approximately 80% of that induced by 10 microM Ca2+. Half-maximum stimulation was induced by 30 microM GTP gamma S or GMPPNP. Both Ca2(+)-stimulated and GTP gamma S-stimulated secretion were ATP dependent and inhibited by N-ethylmaleimide. The GTP gamma S-stimulated secretion of NE from permeabilized PC12 cells does not appear to result from either the release of Ca2+ or the activation of protein kinase C. Activation of protein kinase C by pretreatment of intact cells with 12-O-tetradecanoylphorbol 13-acetate caused a 50% increase in both Ca2(+)-stimulated and GTP gamma S-stimulated secretion. Cholera and pertussis toxins did not affect Ca2(+)-stimulated or GTP gamma S-stimulated NE secretion. Guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) and GTP inhibited GTP gamma S-stimulated secretion but not Ca2(+)-stimulated secretion. The inability of GDP beta S to inhibit Ca2(+)-stimulated secretion indicates that the process affected by GTP gamma S is not an essential step in the Ca2(+)-stimulated pathway.
 ...
PMID:Hydrolysis-resistant GTP analogs stimulate catecholamine release from digitonin-permeabilized PC12 cells. 211 52

A 23 kDa GTP-binding protein was purified from pig heart sarcolemma. This protein was not ADP-ribosylated by cholera, pertussis and botulinum C3 toxins. In pig heart sarcolemma pertussis toxin ADP-ribosylated 40 kDa subunit of Gi-protein, cholera toxin--45 kDa subunit of Gs-protein, botulinum C3 toxin ADP-ribosylated a group of proteins with Mr 22, 26 and 29 kDa. Antiserum generated against the peptide common for all alpha-subunits of G-proteins did not react with purified 23 kDa protein. Trypsin cleaved the 23 kDa protein in the presence of guanyl nucleotides into a 22 kDa fragment. Proteolysis of the 39 kDa alpha 0-subunit from bovine brain plasma membranes and ADP-ribosylated 40 kDa alpha i-subunit from pig heart sarcolemma in the presence of GTP gamma S yielded the 37 and 38 kDa fragments, respectively. In the presence of GTP and GDP the proteolysis of alpha 0 yielded the 24 and 15 kDa fragments, while the proteolysis of ADP-ribosylated alpha i-subunit yielded a labelled 16 kDa peptide. Irrespective of nucleotides trypsin cleaved the ADP-ribosylated 26 kDa substrate of botulinum C3 toxin into two labelled peptides with Mr 24 and 17 kDa. The data obtained indicate the existence in pig heart sarcolemma of a new 23 kDa GTP-binding protein with partial homology to the alpha-subunits of "classical" G-proteins.
 ...
PMID:[Identification and purification of GTP-binding regulatory proteins from plasma membranes of swine heart]. 211 90

Production of the potent lipid autacoid, platelet-activating factor (PAF), is a stimulated response of the endothelium which has important physiologic consequences including mediating adherence of inflammatory cells to the endothelium. Consequently, an understanding of the mechanisms that regulate PAF synthesis by the endothelium is important. To this end, we investigated the role of G proteins as a component of the signal transduction pathway that couples hormonal stimuli to PAF production. The addition of aluminum fluoride (AlF-4) to endothelial cells resulted in production of PAF with a maximal effect at 20 mM fluoride and within 20-60 min of exposure. Alf-4 also augmented the production of PAF which occurs in response to hormonal agonists. In addition, submaximal concentrations of AlF-4 converted an ineffective hormonal agonist (thrombin in bovine cells) to a maximally effective agonist. The adherence of neutrophils to endothelial cells that had been exposed previously to AlF-4 was increased in a manner that paralleled PAF production. PAF production in response to AlF-4 was not consistently affected by pertussis or cholera toxin. Introduction of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) into permeabilized endothelial cells also resulted in PAF production, with reversal by guanosine 5'-O-(2-thiodiphosphate) (GDP beta S), consistent with an effect mediated by a G protein. G protein activation with AlF-4 or GTP gamma S resulted in entry of extracellular Ca2+ as determined using 45Ca2+ flux studies and Indo-1 spectrofluorometry. Our data are consistent with the hypothesis that G proteins couple hormone-receptor binding to opening of a membrane calcium channel, a key step in the initiation of PAF production in endothelial cells.
 ...
PMID:Synthesis of platelet-activating factor by endothelial cells. The role of G proteins. 211 26

Electropermeabilization creates small pores in the plasma membrane allowing the introduction of low-molecular-weight modulatory components, such as ions and nucleotides, into the cytosol. The present study investigates fluoride-mediated stimulation of the signal transduction pathway that activates the respiratory burst in electropermeabilized neutrophils. In marked contrast to intact (i.e., non-electropermeabilized) neutrophils, cells permeabilized by this technique demonstrated an immediate and potent stimulation of the superoxide (O2-)-generating NADPH oxidase in response to the addition of fluoride. Furthermore, permeabilization of neutrophils in the presence of exogenously added ATP enhanced the rate of F(-)-mediated O2- production. Fluoride-stimulated O2- production in electropermeabilized neutrophils was antagonized by GDP beta S and dependent upon the presence of Mg2+ in the medium, but was insensitive to pertussis toxin treatment, consistent with the hypothesis that fluoride activates a G protein, probably Gp, by interacting with the nucleotide-binding site on the G alpha subunit. In addition, electropermeabilized neutrophil O2- release triggered by F- was blocked by staurosporine and H-7, indicating that this pathway proceeds largely through protein kinase C activation. However, nucleotide-enhanced O2- production was only partially blocked by these inhibitors, suggesting that under such conditions ATP either competes with the inhibitor-protein kinase interaction or affects the signaling pathway(s) in such a way that protein kinase C may no longer be necessary for the activation of NADPH oxidase.
 ...
PMID:Fluoride-mediated activation of the respiratory burst in electropermeabilized neutrophils. 211 32

Cholate-solubilized extracts from bovine liver plasma membranes preincubated with the nonhydrolyzable GTP analog guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) displayed enhanced phosphoinositide-specific phospholipase C activity compared with extracts from membranes incubated without nucleotide or with ATP or GDP analog. Resolution of the GTP gamma S-elicited activator of phospholipase C was achieved using heparin-Sepharose which bound the phospholipase C activity. Recombination of non-adsorbed extract with salt-eluted phospholipase C activity resulted in a stimulation of enzyme activity. The GTP gamma S-dependent activator was purified, on the basis of its ability to activate partially purified phospholipase C, by sequential chromatography on Q-Sepharose, Sephacryl S-300, octyl-Sepharose, and Mono Q. The presence of G-protein beta subunits and the alpha subunits of Gi1, Gi2, and Gi3 was detected, by immunoblot analysis, in Mono Q-purified phospholipase C activator preparations. Resolution of the activator from these alpha subunits was achieved by incubation with pertussis toxin in the presence of millimolar NAD+ followed by rechromatography on Mono Q. The phospholipase C activator, thus resolved from ADP-ribosylated alpha i subunits, possessed an approximate Mr of 42 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and copurified with a substoichiometric amount of beta subunit. Immunoblot analysis of fractions from the final Mono Q column revealed cross-reactivity of the 42-kDa phospholipase C activator with antipeptide antibodies raised against residues 160-169 of alpha i1 and a region of sequence common to all known G-protein alpha subunits. The 42-kDa activator was not recognized by other alpha subunit-specific or common antibodies. These findings identify the purified phospholipase C activator as a novel G-protein alpha subunit. This may represent the active subunit of the pertussis toxin-insensitive G-protein mediating receptor-stimulated phosphoinositide breakdown in mammalian liver.
 ...
PMID:Purification from bovine liver membranes of a guanine nucleotide-dependent activator of phosphoinositide-specific phospholipase C. Immunologic identification as a novel G-protein alpha subunit. 212 Feb 13

Gs and Gi2 are G proteins whose alpha subunits are 65% homologous. Within the 355 amino acid alpha i2 polypeptide, substitution of residues Ile213-Lys319 with the corresponding alpha s region (Ile235-Arg356) generated a chimera that activated adenylyl cyclase, indicating that the alpha s activation domain resides within this 122 amino acid alpha s sequence. Mutation within alpha s residues Glu15-Pro144 resulted in an alpha s polypeptide having an enhanced rate of GDP dissociation. Mutation within two regions of the N-terminus influenced the ability of pertussis toxin to ADP-ribosylate the alpha subunit polypeptide, a reaction controlled by the beta gamma subunit complex. The findings define the G protein alpha subunit N-terminus as a regulatory region controlling beta gamma subunit interactions and GDP dissociation independent of the GTPase and effector activation domains.
 ...
PMID:G alpha i-G alpha s chimeras define the function of alpha chain domains in control of G protein activation and beta gamma subunit complex interactions. 212 66

1. Bull-frog dorsal root ganglion cells in primary culture were voltage clamped in the whole-cell configuration. The pipette solution contained ATP (5 mM). 2. Step depolarizations (5-70 mV, 0.1-1 s) from a holding potential close to the resting potential (range, -64 to -79 mV) evoked a non-inactivating potassium current with properties indistinguishable from those which have been reported for the M-current of bull-frog sympathetic neurones. 3. An unhydrolysable ATP analogue APP(NH)P (5 mM), substitute with ATP in the pipette solution, did not support the M-current activation. 4. Bath application of ATP (30 nM-30 microM) reduced the amplitude of the M-current in a concentration-dependent manner, congruent to 50% inhibition of the current occurring with 1 microM-ATP. The main effect of ATP was to reduce the maximum M-conductance without changing the activation and deactivation kinetics of the M-current. 5. Essentially the same results were obtained with ADP (0.1-30 microM) and alpha, beta-methylene-ATP (10-30 microM). AMP (10-100 microM) and adenosine (10-30 microM) were without effect on the M-current. 6. The ATP-induced inhibition of the M-current was irreversible when an unhydrolysable GTP analogue GTP-gamma-S (10-30 microM) was present in the pipette solution. ATP (3 microM) reduced the amplitude of the M-current only by about 10% when GDP-beta-S (100 microM) was present in the pipette solution. Pre-treatment of the cells with pertussis toxin (IAP; 500 ng ml-1) for 24 h at 24 degrees C did not prevent the ATP-induced M-current inhibition. 7. Phorbol 12-myristate 13-acetate (PMA; 1-3 microM) reduced the amplitude of the M-current to about 50%. A reduction in the M-current amplitude by PMA (3 microM) and ATP (10 microM) was attenuated when staurosporine (200 nM) was present in the pipette solution. Forskolin (10 microM) was without effect on the M-current. 8. It is concluded that ATP acting at P2 receptors, associated with an IAP-insensitive GTP-binding protein, inhibits the M-current in amphibian primary afferent neurones.
 ...
PMID:ATP regulates muscarine-sensitive potassium current in dissociated bull-frog primary afferent neurones. 212 60

The mechanism whereby gastrin triggers phosphoinositide breakdown was investigated in an enriched preparation of isolated rabbit parietal cells (approx. 75%). In a permeabilized preparation of myo-[3H]inositol-labelled cells, GTP[S], a non-hydrolysable GTP analogue, enhanced [3H]inositol trisphosphate ([3H]InsP3 accumulation in a dose-dependent manner; submaximal concentrations of GTP[S] (less than 10 microM), potentiated gastrin-induced [3H]InsP3 release; preincubation for 5 min with GDP[S], a non-hydrolysable GDP analogue, dose-dependently reduced [3H]InsP3 accumulation stimulated by gastrin even in presence of GTP[S]. Exposure of intact parietal cells for 3 h to pertussis toxin (PTx) (200 ng/ml) led to a 15-50% reduction in gastrin-induced [14C]aminopyrine [(14C]AP) uptake (an index of in vitro acid secretion) and [3H]inositol phosphate ([3H]InsP) accumulation. A decrease in the accumulation of the different [3H]inositol phosphate occurred in gastrin-stimulated parietal cells treated with PTx. A rightward shift of gastrin dose-response curves in the presence of PTx was observed for [14C]AP uptake (EC50 values: 0.125 +/- 0.045 nM without PTx and 1.05 +/- 0.63 nM with PTx), for [3H]InsP accumulation (EC50 values: 0.16 +/- 0.08 nM without PTx and 1.56 +/- 0.58 nM with PTx) and [125I]gastrin binding (IC50 values: 0.247 +/- 0.03 nM without PTx and 2.38 +/- 0.56 nM with PTx). In contrast, cholera toxin (CTx) treatment (100 ng/ml) for 3 h was without effect on gastrin-induced [3H]InsP accumulation. CTx induced a pronounced potentiation of gastrin-stimulated [14C]AP uptake; this effect can be mimicked by IBMX (a phosphodiesterase inhibitor) and by forskolin (an activator of adenylyl cyclase). We conclude that: (i) one or more than one G protein appeared to be involved in gastrin receptor coupling to phospholipase C (PL-C); (ii) these G proteins are not substrates for CTx; (iii) one of these appeared to be a PTx-sensitive 'Gi-like' protein which could be involved in hormone-induced acid secretion, (iiii) the potentiating effect of CTx observed on AP uptake stimulated by gastrin suggests the existence of a cooperative effect between cAMP pathway (CTx) and the gastrin-induced phosphoinositide breakdown in acid secretory activity of parietal cells.
 ...
PMID:Involvement of a pertussis toxin-sensitive G protein in the action of gastrin on gastric parietal cells. 212 30


<< Previous 1 2 3 4 5 6 7 8 9 10