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)

Guinea pig hepatocytes fractionated by differential centrifugation into plasma membrane-enriched, microsomal, and cytosolic fractions were examined for their content of alpha and beta subunits of heterotrimeric GTP-binding proteins (G proteins) involved in signal transduction. alpha subunits of stimulatory (Gs) and inhibitory (Gi) proteins were detected by immunoblots with antisera reactive with the carboxyl-terminal decapeptide regions of these proteins. Unexpectedly, antisera (including immunopurified) to the alpha subunit but not the beta subunit reacted with a band of 100-kDa proteins in both the microsomal and cytosolic fractions. The immunoreactive 100-kDa proteins are not substrates for ADP-ribosylation catalyzed by pertussis toxin, cholera toxin, or diptheria toxin. Protease digests of the 100-kDa proteins yielded immunoreactive peptides that are distinctly different from those obtained from protease digests of alpha subunits of heterotrimeric G proteins. The 100-kDa protein(s) reactive with antisera to Gi alpha subunit bind to GTP-agarose but not to ATP-agarose. It is concluded that the immunoreactive 100-kDa proteins in microsomal and cytosolic fractions are structurally distinct G proteins from those linked to receptors in the plasma membrane and other G proteins such as elongation factor 2. Conceivably, the 100-kDa proteins represent a new class of G proteins.
 ...
PMID:Microsomal and cytosolic fractions of guinea pig hepatocytes contain 100-kilodalton GTP-binding proteins reactive with antisera against alpha subunits of stimulatory and inhibitory heterotrimeric GTP-binding proteins. 169 25

Exposure of rat heart muscle cells to noradrenaline (1 microM) for 48 hr led to a decrease in the number of beta 1-adrenoceptors of 50% and a concomitant decrease in adenylyl cyclase stimulation by isoprenaline and forskolin of about 60 and 30%, respectively. In addition, the levels of two inhibitory guanine nucleotide-binding protein (Gi protein) alpha-subunits (Gi alpha 40 and Gi alpha 41) were increased in membranes of noradrenaline-treated cells. Evidence is presented that noradrenaline induces this increase by activation of beta-adrenoceptors. First, the noradrenaline action was mimicked by the beta-adrenoceptor agonist isoprenaline. Second, beta-adrenoceptor blockade by timolol but not alpha-adrenoceptor blockade by prazosin prevented the noradrenaline-induced up-regulation of Gi alpha proteins. Furthermore, timolol but not prazosin abolished the noradrenaline-induced down-regulation of beta 1-adrenoceptors and the decreases in receptor-dependent (isoprenaline) and -independent (forskolin) adenylyl cyclase stimulation. The specific protein synthesis inhibitor Pseudomonas exotoxin A was used to study whether the noradrenaline-induced up-regulation of Gi alpha subunits depends on increased synthesis of these proteins. This toxin inhibits peptide chain elongation by ADP-ribosylating elongation factor 2. Treatment of rat heart muscle cells with Pseudomonas exotoxin A (1 ng/ml) completely prevented the noradrenaline-induced increase in Gi alpha proteins, measured by both pertussis toxin-catalyzed ADP-ribosylation and immunoblotting with anti-Gi alpha antibodies. Most importantly, Pseudomonas exotoxin A also completely prevented the noradrenaline-induced decrease in forskolin-stimulated adenylyl cyclase activity. Furthermore, the noradrenaline-induced decrease in isoprenaline-stimulated adenylyl cyclase activity was significantly attenuated by the toxin, although the down-regulation of beta 1-adrenoceptors caused by noradrenaline treatment was not affected. The data presented suggest that prolonged activation of beta-adrenoceptors in rat heart muscle cells, in addition to causing a receptor down-regulation, induces the synthesis of Gi alpha proteins, which then apparently mediate a decreased adenylyl cyclase responsiveness. The data, additionally, suggest that the synthesis of Gi alpha proteins is under control of the activity of the adenylyl cyclase system and that altered levels of these proteins may play a major role in long term regulation of signal transduction by this enzyme.
 ...
PMID:Pseudomonas exotoxin A prevents beta-adrenoceptor-induced upregulation of Gi protein alpha-subunits and adenylyl cyclase desensitization in rat heart muscle cells. 197 Oct 89

ADP-ribosylation of regulatory proteins is an important pathological mechanism by which various bacterial toxins affect eukaryotic cell functions. While diphtheria toxin catalyses the ADP-ribosylation of elongation factor 2, which results in inhibition of protein synthesis, cholera toxin and pertussis toxin ADP-ribosylate Ns and Ni, respectively, the GTP-binding regulatory components of the adenylate cyclase system, thereby modulating the bidirectional hormonal regulation of the adenylate cyclase. Botulinum C2 toxin is another toxin which has been reported to possess ADP-ribosyltransferase activity. This extremely toxic agent is produced by certain strains of Clostridium botulinum and induces hypotension, an increase in intestinal secretion, vascular permeability and haemorrhaging in the lungs. In contrast to botulinum neurotoxins, the botulinum C2 toxin apparently lacks any neurotoxic effects. Here we report that botulinum C2 toxin ADP-ribosylates a protein of relative molecular mass 43,000 (43K) in intact cells and in cell-free preparations. We present evidence that the 43K protein substrate is actin, which is apparently mono-ADP-ribosylated by the toxin. Botulinum C2 toxin also ADP-ribosylated purified liver G-actin, whereas liver F-actin was only poorly ADP-ribosylated and skeletal muscle actin was not ADP-ribosylated in either its G form or its F form. ADP-ribosylation of liver G-actin by botulinum C2 toxin resulted in a drastic reduction in viscosity of actin polymerized in vitro.
 ...
PMID:Botulinum C2 toxin ADP-ribosylates actin. 373 64

Exposure of neonatal rat cardiomyocytes for 3 days to the muscarinic cholinoceptor agonist carbachol led to a concentration-dependent increase in adenylyl cyclase stimulation by the beta-adrenoceptor agonist isoproterenol by up to 115% (at 1 mmol/l carbachol). In addition, direct adenylyl cyclase stimulation by forskolin was increased in carbachol (1 mmol/l)-treated cells by 32%. Pretreatment of the rat cardiomyocytes with pertussis toxin, which enhances adenylyl cyclase activity by a functional inactivation of the inhibitory G-protein (Gi), was performed to investigate the possible role of Gi-proteins in carbachol-induced sensitization of adenylyl cyclase stimulation. After pretreatment of the cells with pertussis toxin, the carbachol-mediated increase in forskolin-stimulated adenylyl cyclase activity was lost and the carbachol-mediated increase in beta-adrenoceptor-stimulated adenylyl cyclase activity was attenuated. Labelling of the 40 kDa pertussis toxin substrates in cardiomyocyte membranes was decreased by carbachol in a concentration-dependent manner by up to 34% (at 1 mmol/l carbachol). The number and affinity of beta 1-adrenoceptors was unaltered following the chronic carbachol treatment. The specific protein synthesis inhibitor Pseudomonas exotoxin A was used to study whether the carbachol-induced decrease in the level of pertussis toxin-sensitive G-proteins and increase in adenylyl cyclase activity depend on de-novo protein synthesis. Pseudomonas exotoxin A inhibits peptide chain elongation by ADP-ribosylating elongation factor 2. Treatment of the cells with 1 ng/ml Pseudomonas exotoxin A for 3 days led to a reduction in the subsequent ADP-ribosylation of elongation factor 2 in the cytosol of the heart muscle cells by 57%.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Chronic muscarinic cholinoceptor stimulation increases adenylyl cyclase responsiveness in rat cardiomyocytes by a decrease in the level of inhibitory G-protein alpha-subunits. 771 38

A rat glycohydrolase which catalyzes the hydrolysis of ADP-ribosylarginine was expressed in Escherichia coli and purified to homogeneity for characterization of its enzymatic properties. The purified glycohydrolase catalyzed the hydrolysis of N-glycoside linked ADP-ribosylarginine on the alpha-subunits of stimulatory GTP-binding proteins (Gs) and cholera toxin A1-subunit that had been modified by cholera toxin and NAD. Nonmuscle actin of which an arginine residue was ADP-ribosylated by botulinum C2 toxin also served as a substrate of the glycohydrolase. On the other hand, the glycohydrolase did not hydrolyze ADP-ribosylated cysteine on the alpha-subunits of pertussis toxin-substrate GTP-binding proteins, ADP-ribosylated diphthamide on elongation factor 2, or ADP-ribosylated asparagine on rho GTP-binding proteins. The rate of the reaction catalyzed by the glycohydrolase was affected by nucleotide-binding form of the ADP-ribosylated substrate proteins; the GDP-bound form of the modified Gs-alpha was more rapidly hydrolyzed than the guanosine 5'-(3-O-thio)triphosphate-bound form. Interestingly, the glycohydrolase activity was markedly inhibited by mM order concentration of ATP in addition to ADP-ribose, the product of the enzyme reaction, though ADP had no inhibitory effect on the activity. Moreover, alpha NAD, but not beta NAD, inhibited the enzyme activity, suggesting that the glycohydrolase reaction was stereospecific for the alpha-anomer.
 ...
PMID:ADP-ribosylarginine glycohydrolase catalyzing the release of ADP-ribose from the cholera toxin-modified alpha-subunits of GTP-binding proteins. 789 43

Arginine-specific mono-ADP-ribosylation of proteins and arginine-specific mono-ADP-ribosyltransferase occur in heart. We developed a polyclonal antiserum, R-28, against ADP-ribosylpolyarginine that recognized mono-ADP-ribosylated proteins and identified the major mono-ADP-ribosylation products of quail heart. Treatment of Immobilon-bound ADP-ribosylated Gs protein with hydroxylamine under conditions that remove ADP-ribose from its arginines eliminated R-28 immunoreactivity to Gs. Also, R-28 immunoreactivity to quail heart proteins was removed by NaOH and phosphodiesterase I treatments. Similar treatment with mercuric chloride did not remove the immunoreactivity but did remove exogenously (via in vitro pertussis toxin treatment) added ADP-ribose from cysteine of cardiac Gi/Go proteins. The antiserum did not appear to react with ADP-ribosylasparagine of Rho (formed by C3 toxin), ADP-ribosyldiphthamide of elongation factor 2 (formed by diphtheria toxin) in quail heart preparations, or polyADP-ribosylated proteins of a neonate rat cardiac nuclear preparation. Thus, the R-28 antiserum appears to contain predominantly antibodies directed against ADP-ribosylarginine. To test the usefulness of R-28, immunoblotting of subcellular fractions of quail heart was performed. R-28 showed the greatest immunoreactivity in the sarcolemma with significant immunoreactivity in denser membrane fractions. The cytosol also contained an immunoreactive band distinct from those found in the membranes. Hydroxylamine treatment eliminated immunoreactivity in the sarcolemma and denser membrane fractions but not the cytosol, suggesting the membranous immunoreactive bands contain ADP-ribosylarginine. In conclusion, a polyclonal antiserum that recognizes ADP-ribosylarginine proteins has been raised. The usefulness of the antiserum is demonstrated by the characterization of endogenous arginine mono-ADP-ribosylation products in quail heart. The quail heart has several sarcolemmal and denser membrane fraction proteins that appear to be mono-ADP-ribosylated on arginines.
 ...
PMID:Evidence of endogenous mono-ADP-ribosylation of cardiac proteins via anti-ADP-ribosylarginine immunoreactivity. 1072 Oct 9

Bacterial protein toxins are the most powerful human poisons known, exhibiting an LD(50) of 0.1-1 ng kg(-)(1). A major subset of such toxins is the NAD(+)-dependent ADP-ribosylating exotoxins, which include pertussis, cholera, and diphtheria toxin. Diphtheria toxin catalyzes the ADP ribosylation of the diphthamide residue of eukaryotic elongation factor 2 (eEF-2). The transition state of ADP ribosylation catalyzed by diphtheria toxin has been characterized by measuring a family of kinetic isotope effects using (3)H-, (14)C-, and (15)N-labeled NAD(+) with purified yeast eEF-2. Isotope trapping experiments yield a commitment to catalysis of 0.24 at saturating eEF-2 concentrations, resulting in suppression of the intrinsic isotope effects. Following correction for the commitment factor, intrinsic primary kinetic isotope effects of 1.055 +/- 0.003 and 1.022 +/- 0.004 were observed for [1(N)'-(14)C]- and [1(N)-(15)N]NAD(+), respectively; the double primary isotope effect was 1.066 +/- 0.004 for [1(N)'-(14)C, 1(N)-(15)N]NAD(+). Secondary kinetic isotope effects of 1.194 +/- 0.002, 1.101 +/- 0.003, 1.013 +/- 0.005, and 0.988 +/- 0.002 were determined for [1(N)'-(3)H]-, [2(N)'-(3)H]-, [4(N)'-(3)H]-, and [5(N)'-(3)H]NAD(+), respectively. The transition state structure was modeled using density functional theory (B1LYP/6-31+G) as implemented in Gaussian 98, and theoretical kinetic isotope effects were subsequently calculated using Isoeff 98. Constraints were varied in a systematic manner until the calculated kinetic isotope effects matched the intrinsic isotope effects. The transition state model most consistent with the intrinsic isotope effects is characterized by the substantial loss in bond order of the nicotinamide leaving group (bond order = 0.18, 1.99 A) and weak participation of the attacking imidazole nucleophile (bond order = 0.03, 2.58 A). The transition state structure imparts strong oxacarbenium ion character to the ribose ring even though significant bond order remains to the nicotinamide leaving group. The transition state model presented here is asymmetric and consistent with a dissociative S(N)1 type mechanism in which attack of the diphthamide nucleophile lags behind departure of the nicotinamide.
 ...
PMID:Transition state structure for ADP-ribosylation of eukaryotic elongation factor 2 catalyzed by diphtheria toxin. 1475 56