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)

We studied the mechanisms underlying the increase in automaticity induced by alpha 1-adrenergic stimulation of normal and "ischemic" canine Purkinje fibers. Fibers were superfused with a control Tyrode's solution, followed by an ischemic superfusate that included 10 mM KCl, 5 mM NaHCO3, Po2 of 10-25 mm Hg, and pH 6.7. To exclude beta-adrenergic actions, propranolol was added to all solutions. In the presence of phenylephrine, normal automaticity at high membrane potentials usually decreased, whereas the incidence of abnormal automaticity during ischemia was increased from a control value of 10% to 30%. Block of an alpha 1-receptor subtype with chloroethylclonidine in the presence of phenylephrine caused normal automaticity to increase in all fibers studied and significantly increased abnormal automaticity to 70%. The alpha-adrenergic-induced increase in automaticity did not occur in ischemic fibers from animals pretreated with pertussis toxin (PTX), which ADP-ribosylated and functionally inactivated the 41-kd family of GTP regulatory proteins. In contrast, the use of PTX enhanced the increase in automaticity induced by phenylephrine in normally polarized Purkinje fibers. Ryanodine, which blocks sarcoplasmic reticulum Ca2+ release, attenuated the increase in normal automaticity in nonischemic fibers but had no effect on abnormal automaticity in ischemic fibers. The increase in abnormal automaticity was, however, blocked by the alpha 1 subtype blocker WB 4101, which also blocks the increase in automaticity in normal fibers. In conclusion, the increase in abnormal automaticity in ischemic Purkinje fibers depends on a WB 4101-sensitive alpha 1-adrenergic receptor subtype whose actions are transduced by a PTX-sensitive 41-kd G protein and are not blocked by ryanodine.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Positive chronotropic responses induced by alpha 1-adrenergic stimulation of normal and "ischemic" Purkinje fibers have different receptor-effector coupling mechanisms. 132 30

We have previously reported the selective amplification of several rat striatal cDNA sequences that encode guanine nucleotide-binding regulatory protein (G protein)-coupled receptors. One of these sequences (R226) exhibited high sequence identity (58%) with the two previously cloned adenosine receptors. A full-length cDNA clone for R226 has been isolated from a rat brain cDNA library. The cDNA clone encodes a protein of 320 amino acids that can be organized into seven transmembrane stretches. R226 has been expressed in COS-7 and CHO cells and membranes from the transfected cells were screened with adenosine receptor radioligands. R226 could bind the nonselective adenosine agonist tritiated N-ethyladenosine 5'-uronic acid ([3H]NECA) and A1-selective agonist radioiodinated N6-2-(4-amino-3-iodophenyl)-ethyladenosine ([125I]APNEA) but not A1-selective antagonists tritiated 1,3-dipropyl-8-cyclopentylxanthine ([3H]DPCPX) and 8-(4-[([[(2-aminoethyl)amino]carbonyl]methyl)oxy]-phenyl)-1, 3-dipropylxanthine ([3H]XAC) or the A2-selective agonist ligands tritiated 2-[4-(2-carboxyethyl)phenyl]ethyl-amino 5'-N-ethylcarboxamidoadenosine ([3H]CGS21680) and radioiodinated 2-[4-([2-[(4-aminophenyl)methylcarbonylamino] ethylaminocarbonyl]ethyl)phenyl]ethylamino 5'-N-ethylcarboxamidoadenosine. Extensive characterization with [125I]APNEA showed that R226 binds [125I]APNEA with high affinity (Kd = 15.5 +/- 2.4 nM) and the specific [125I]APNEA binding could be inhibited by adenosine ligands with a potency order of (R)-N6-phenyl-2-propyladenosine (R-PIA) = NECA greater than S-PIA greater than adenosine greater than ATP = ADP but not by antagonists XAC, isobutylmethylxanthine, and DPCPX. In R226 stably transfected CHO cells, adenosine agonists R-PIA, NECA, and CGS21680 inhibited by 40-50% the forskolin-stimulated cAMP accumulation through a pertussis toxin-sensitive G protein with an EC50 of 18 +/- 5.6 nM, 23 +/- 3.5 nM, and 144 +/- 34 nM, respectively. Based on these observations we conclude that R226 encodes an adenosine receptor with non-A1 and non-A2 specificity, and we thus name it the A3 adenosine receptor. mRNA analyses revealed that the highest expression of R226 was in the testis and low-level mRNAs were also found in the lung, kidneys, heart, and some parts of the central nervous system such as cortex, striatum, and olfactory bulb. The high-expression level of the A3 receptor in the testis suggests a possible role for adenosine in reproduction.
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PMID:Molecular cloning and characterization of an adenosine receptor: the A3 adenosine receptor. 132 36

Preincubation of human peripheral blood polymorphonuclear leukocytes (HPPMN) with recombinant human tumor necrosis factor-alpha (rHuTNF-alpha) enhanced the formylmethionyl-leucylphenylalanine (FMLP)-induced superoxide (O2-.) generation in a concentration- and preincubation time-dependent manner. The enhancement was very high for the FMLP- or opsonized zymosan (OZ)-induced O2-. generation, but was low for arachidonic acid (AA)- and phorbol myristate acetate (PMA)-induced O.2- generation. The rHuTNF-alpha has no effect on the steady state of intracellular calcium ion concentration ([Ca2+]i) nor on the membrane potential of neutrophils. The rHuTNF-alpha-primed FMLP-induced O2-. generation was inhibited by nicotineamide (NA), pertussis toxin (PT), and by the tyrosine kinase (TK) inhibitor, genistein, but was enhanced by the protein kinase C (PKC) inhibitor, H-7 (1-(5-isoquinolinesulfonyl)-3-methyl-piperazine). The inhibitory actions of NA and PT were also observed in in vivo primed guinea pig peritoneal neutrophils (GPtPMN). However, FMLP-induced O2-. generation of GPtPMN was enhanced by genistein, but was inhibited by H-7. These data indicate that TNF-alpha does not induce changes in [Ca2+]i nor in membrane potential of HPPMN, and that TNF-alpha-primed FMLP-induced O.2- generation of HPPMN is coupled with ADP-ribosylation and activation of G-proteins, and that protein kinases, especially TK, seem to exert an important role in the priming action of TNF.
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PMID:Effect of tumor necrosis factor-alpha on the stimulus-coupled responses of neutrophils and their modulation by various inhibitors. 132 5

This study investigates interaction of bombesin receptors with heterotrimeric guanosine triphosphate (GTP)-binding proteins (G proteins) and monomeric small molecular weight GTP-binding proteins (smg proteins), respectively, in plasma membranes (PM) of rat pancreatic acinar cells. Addition of bombesin to isolated PM stimulated the incorporation of the photoaffinity analogue [alpha-32P]GTP-gamma-azidoanilide into Gi proteins of 40-41 kDa and reduced the pertussis toxin-induced ADP ribosylation of three 40-41 kDa proteins, which had been previously identified as Gi1, Gi2, and Gi3 (30). In PM isolated from bombesin-prestimulated acinar cells, binding of [alpha-32P]-GTP to PM proteins of 21-22 kDa and of a monoclonal antibody against p21ras proteins was increased. Two-dimensional separation of PM proteins revealed the presence of 18 or 19 differently charged smg proteins. The p21ras proteins could be separated into two differently charged proteins with isoelectric points of 5.58 and 5.79. In microsomal membranes (MM), [alpha-32P]GTP binding to yet unidentified 21-22 kDa smg proteins was decreased compared with membranes from unstimulated acinar cells. The data suggest that Gi proteins as well as p21ras proteins are involved in bombesin receptor-mediated signal transduction in the PM. Furthermore, 21-22 kDa smg proteins in MM might play a role in bombesin-induced stimulation of intracellular pathways that lead to enzyme secretion from pancreatic acinar cells.
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PMID:Bombesin receptors interact with Gi and p21ras proteins in plasma membranes from rat pancreatic acinar cells. 132 28

Neoplastic Jurkat cells were submitted to a PHA stimulation test after a preincubation in maternal or nulliparous serum (10% dilution). The Il2R expression was significantly downregulated among maternal serum treated cells. Retroplacental serum was significantly more inhibitive than peripheral maternal serum (P less than 0.01). The maternal IgG fractions and mostly the retroplacental IgG fraction proved to contain a factor mainly responsible for the Il2R expression inhibitive property. The molecular mechanism of this phenomenon was further studied. It was shown that H7 (acting as a protein kinase inhibitor) could not influence the Il2R modulation. E.G.T.A., a calcium chelator, was not able to interfere with the inhibitive influence of maternal serum. It was suggested that the maternal serum mediated inhibition of the IL2R expression is not influenced by the hydrolysis of membrane bound phosphatidyl inositol. In contrast, pertussis toxin markedly enhanced, in a dose dependent way, the suppressive influence of maternal serum as compared to nulliparous serum. At low concentrations, pertussis toxin lost its stimulating property and retained its ability to ADP ribosylate the alpha subunit of G proteins inducing a release of adenylcyclase mediating cAMP synthesis. This mechanism has been further studied by the addition of dbc AMP or dbc GMP to Jurkat cells preparations stimulated by PHA. dbc AMP, in a dose-related way, induced a downregulation of the IL2R expression of stimulated neoplastic cells preincubated in nulliparous or maternal serum. dbc GMP did not influence the IL2R expression in the same experimental conditions. The maternal serum mediated cells showed the most pronounced IL2R inhibition. Finally, it was shown that the cAMP synthesis by PHA stimulated Jurkat cells was upregulated in a dose dependent way, after a previous cellular incubation in progressive concentrations of maternal serum. In contrast, among nulliparous serum pretreated cells, cAMP synthesis remained significantly lower, after a lectin stimulation, as compared to the cAMP production derived from retroplacental serum treated and stimulated cells. Taken together, these experiments suggest that the maternal serum dependent suppression of the IL2R expression is related to a protein G stimulation followed by an enhanced cAMP synthesis.
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PMID:Mechanism of action of maternal serum on the interleukin2 receptor expression. 132 91

The effects of the cholinergic agonist carbachol (Cch) and guanine nucleotides on the Na,K-ATPase and K-dependent p-nitrophenylphosphatase (K-p-NPPase) activities in rabbit and dog myocardial sarcolemma vesicles in the presence of the pore-forming antibiotic alamethicin (20 micrograms/ml), was studied. Cch (0.01-100 microM) inhibited the both enzymatic activities by 40-45% (IC50 = 0.3-0.5 microM) only after addition of GTP (50 microM) or its analogs: GTP gamma S (0.1-1.0 microM) and Gpp(NH)p (10 microM). The muscarinic acetylcholine receptor (mAchR) antagonist atropine (10 microM) blocked the effect of Cch. GTP gamma S alone produced a concentration-dependent decrease in the both Na,K-ATPase and K-p-NPPase activities by 40-45% (IC50 = 1-2 microM) with a lag period of about 3 minutes; this lag disappeared in the presence of the agonist. The GDP analog GDP beta S (0.01-100 microM) neither affected these activities nor promoted the inhibiting effect of Cch. Pretreatment of sarcolemmal vesicles with 20 micrograms/ml of pertussis toxin in the presence of 100 microM NAD abolished the inhibiting effect of Cch on the Na,K-ATPase and phosphatase activities. Under these conditions pertussis toxin catalyzed the ADP-ribosylation of alpha-subunits of the inhibitory GTP-binding protein (G1) which were identified immunochemically as alpha i2, alpha i3 and, possibly, alpha i1. The data obtained testify to the involvement of G1 in the mAchR-mediated inhibition of myocardial sarcolemmal Na,K-ATPase as well as in the signal transduction from the receptor to the enzyme.
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PMID:[The role of a GTP-binding protein in coupling of a muscarinic cholinergic receptor and Na,K-ATPase in myocardial sarcolemma]. 132 37

Identification of G-proteins and coupling of PAF receptors to G-proteins have been examined in the membranes of human blood eosinophils and neutrophils. Heterotrimeric G-proteins, Gi and GS, were present in both cell types, as demonstrated by immunoblotting and ADP-ribosylation with pertussis toxin. In addition, a group of low molecular mass (18-28 kDa) monomeric G-proteins was also identified. Pertussis toxin and GTP gamma S attenuated the specific binding of [3H]PAF, suggesting the occurrence of coupling between pertussis toxin-sensitive Gi protein and PAF receptors in eosinophils and neutrophils.
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PMID:PAF receptors and G-proteins in human blood eosinophils and neutrophils. 132 43

Membranes from highly purified natural killer (NK) cells were ADP ribosylated by treatment with pertussis toxin (PTX). PTX treatment resulted in a single band of 32P incorporation at M(r) 41,600. PTX treatment of NK cells diminished their ability to lyse K562 tumour cells by about 50%. However PTX treatment had no measurable effect on cAMP levels in NK cells. PTX pretreatment also had no effect on the ability of target cells to induce phosphoinositide turnover or on the ability of the NK cells to conjugate with the K562 tumour cells. Movement toward the chemoattractants interleukin-2 (IL-2) and formylmethionylleucylphenylalanine (FMLP) was significantly inhibited indicating that a PTX substrate in NK cells may be involved in the transduction of signals which are involved in cell motility.
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PMID:Effects of pertussis toxin treatment on human natural killer cell function. 132 77

Transducin, a retinal G-protein, has been shown to exist as heterotrimers of alpha (39,000), beta (36,000), and gamma (approximately 7,000) subunits. Blue Sepharose CL-6B column chromatography of a transducin preparation extracted with a metal-free, low salt buffer containing GTP showed three distinct alpha and two distinct beta gamma activities in frog (Rana catesbeiana) rod outer segment. The binding of a hydrolysis-resistant GTP analog in these alpha fractions was proportional to the amount of the M(r) 39,000 protein. The first alpha was eluted in a complex with an inhibitory subunit of cGMP phosphodiesterase, but alpha subunits in the second and the third fractions were not complexed with any proteins. Two-dimensional gel electrophoresis and characterization with regard to the interaction with the inhibitory subunit of cGMP phosphodiesterase suggested that the first and the second alpha s were the same protein; however, the third alpha showed different characters as follows. We designated alpha in the first two fractions as alpha 1, and alpha in the third fraction as alpha 2. Nonlinear regression analysis for the binding of a hydrolysis-resistant GTP analog to both alpha subunits revealed a single class of GTP binding sites with an apparent stoichiometry of 1 mol of GTP/mol of alpha. Compared with alpha 1, alpha 2 required larger amounts of rhodopsin and beta gamma for the binding of a hydrolysis-resistant GTP analog. alpha 2 also showed less binding with the inhibitory subunit of cGMP phosphodiesterase. Both alpha 1 and alpha 2 complexed with beta gamma or beta delta (described below) were substrates for pertussis toxin-dependent ADP-ribosylation. The protein profiles of two beta gamma fractions revealed that the main fraction was composed of a beta gamma complex; however, the second active fraction was composed of beta complexed with delta (M(r) 12,000). Compared with beta gamma, beta delta stimulated GTP binding to alpha 1 at approximately 10-fold higher concentration. Two-dimensional gel electrophoresis revealed five beta and two gamma isoforms in beta gamma. Only one beta isoform was present in beta delta. The diversity of transducin subunits may reflect different signaling pathways in visual signal transduction.
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PMID:Heterogeneity of the retinal G-protein transducin from frog rod photoreceptors. Biochemical identification and characterization of new subunits. 132 54

We have examined the isolated postsynaptic density (PSD) fraction for the presence of a G protein. First, we found specific binding of guanosine 5'-[gamma-[35S]thio]triphosphate to the PSD. Second, pertussis toxin-activated ADP-ribosylation of the isolated PSD fraction resulted in the appearance of a G protein with an apparent molecular mass of 41 kDa, and two G proteins with apparent molecular masses of 41 kDa and 39 kDa in synaptic membrane (SM) fraction and total homogenate (H). The amount of the 41-kDa G protein per unit protein was in the order of SM greater than H greater than PSD. Anti-G(i0 antibodies recognized the 41-kDa G protein in both PSD and SM, whereas anti-G(o) antibodies reacted with the 39-kDa G protein in the SM. The absence of G(o) protein in the PSD suggested that there was no contamination with SM. Moreover, unlabeled PSD incubated with an extract of SM that contained the labeled G proteins resulted in no label in the subsequently reisolated PSD, suggesting that the G protein found in the PSD was not due to adsorption of the G protein onto the PSD during its isolation from the SM. PSD pretreated with EGTA gave an 11-fold increase in the ADP-ribosylation reaction of the G(i) protein; similar effects on the G(i) and G(o) proteins of SM were obtained. Restoration of Ca2+/calmodulin to the PSD, but not of either Ca2+ or calmodulin alone, removed the effect of EGTA, indicating a strong complex formation between G(i) and Ca2+/calmodulin that decreased the ADP-ribosylation reaction. Preincubation with the Ca(2+)-channel blocker nifedipine decreased the ADP-ribosylation reaction in the PSD. We conclude that G(i) is present in the PSD, that it may interact with calmodulin and that it is involved in the regulation of voltage-dependent Ca2+ channel. We present a theory of the involvement of the G protein and calmodulin in postsynaptic neurophysiological events.
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PMID:Occurrence of the alpha subunits of G proteins in cerebral cortex synaptic membrane and postsynaptic density fractions: modulation of ADP-ribosylation by Ca2+/calmodulin. 132 62


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