Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Human hearts with idiopathic dilated cardiomyopathy have diminished adenylate cyclase activity and increased amounts of the alpha-subunit of the inhibitory guanine nucleotide-binding regulatory protein (alpha Gi) as measured by pertussis toxin catalyzed ADP-ribosylation. We utilized specific antisera against synthetic peptides corresponding to amino sequences deduced from cDNA's encoding the three alpha Gi subspecies to compare the immunologic and bioactivity levels of Gi in failing and non-failing human hearts. The various antisera detected three peptides with Mr 42,000, 38,000, and 37,000. Only the Mr 42,000 peptide co-migrated with the pertussis toxin substrate. Although functional activity of alpha Gi was increased in the particulate fractions of the failing heart as measured by inhibition of guanine nucleotide-stimulated adenylate cyclase activity and the quantity of pertussis toxin substrate was also increased, there were not associated changes in the levels of immunodetectable Gi. Therefore, the increased functional activity of Gi in the failing human heart as assessed by adenylate cyclase measurements cannot be explained by a relative increase in the among of Gi protein.
J Mol Cell Cardiol 1991 Apr
PMID:Immunodetectable levels of the inhibitory guanine nucleotide-binding regulatory proteins in failing human heart: discordance with measurements of adenylate cyclase activity and levels of pertussis toxin substrate. 194 80

Extracellular ATP and UTP produced a rapid accumulation of inositol phosphates in human airway epithelial cells (CF/T43). The order of agonist potencies for a series of nucleotide analogues differed markedly from that of the classically described P2x- or P2y-purinergic receptors. UTP was the most potent agonist and was fully efficacious; ATP and adenosine-5'-O-(3-thiotriphosphate) were also full agonists. In contrast, 2-methylthio-ATP, adenosine-5'-O-(2-thiodiphosphate) and alpha,beta-methylene-ATP were without effect. ADP and UDP had little or no effect at concentrations as high as 100 microM, and deoxyribose and dideoxyribose compounds were inactive. The effects of ATP and UTP were not additive, whereas bradykinin- or histamine-stimulated inositol phosphate production was additive with the effects of ATP or UTP. Preincubation of cells with either UTP or ATP resulted in a parallel loss of responsiveness to both agonists. Desensitization was specific for the response to nucleotides, because no ATP- or UTP-induced effect on the response to histamine or bradykinin was observed. Pertussis toxin treatment of CF/T43 cells produced a 30-40% decrease in the response to ATP or UTP, which correlated with the ADP-ribosylation of 41- and 43-kDa proteins. Bradykinin and histamine responses were not modified by pertussis toxin. Guanine nucleotides had little effect on the inositol phosphate response in intact CF/T43 cells at concentrations below 100 microM. However, in streptolysin-O-permeabilized cells GTP-gamma S produced a concentration-dependence activation of inositol phosphate formation. UTP or ATP had little effect in permeabilized cells in the absence of guanine nucleotides but markedly increased inositol phosphate formation in the presence of guanine nucleotides. Taken together, these results suggest that UTP and ATP activate a 5'-nucleotide receptor on CF/T43 cells that is distinct from the classically defined P2x- and P2y-purinergic receptors. Activation of phospholipase C by this receptor involves, at least in part, a guanine nucleotide-binding regulatory protein.
Mol Pharmacol 1991 Nov
PMID:Evidence that UTP and ATP regulate phospholipase C through a common extracellular 5'-nucleotide receptor in human airway epithelial cells. 194 36

To investigate the relationship between the effects of a pertussis toxin-inhibitable class of G-proteins and the ras family of protooncogenes on cell growth, we isolated multiple cell lines transformed by oncogenic Hras or Nras genes and measured the ability of pertussis toxin to inhibit their growth rate. Although all of the cell lines were morphologically transformed and could grow in agar suspension, there was considerable variability in their resistance to pertussis toxin, ranging from cell lines completely resistant to pertussis toxin to cell lines as sensitive to pertussis toxin as the parental cells from which they derived. For those lines resistant to pertussis toxin, this resistance is not due to an inability of pertussis toxin to reach or react with its intracellular target; pertussis toxin could be shown to ADP-ribosylate the endogenous G-proteins of all lines tested regardless of whether it affected their growth rate. There was a strong correlation between the level of active ras protein expressed in the different lines and the degree of resistance to pertussis toxin (r = 0.80). Although the Hras-transformed cell lines were more resistant to pertussis toxin as a group than the Nras-transformed cell lines, we believe that this is not a primary difference between Nras and Hras, but, rather, is due to a higher average level of expression of ras in the cell lines receiving Hras. We suggest that the consequences of ras transformation vary with the concentration of oncogenic ras present in the cell, and that different assays or different properties of transformation show different sensitivities to the level of ras expression.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1991 Aug
PMID:Effect of ras-gene transformation on the inhibition of NIH3T3 cell growth by pertussis toxin. 194 6

The first step in net active transepithelial transport of sodium in tight epithelia is mediated by the amiloride-blockable sodium channel in the apical membrane. This sodium channel is the primary site for discretionary control of total body sodium and, therefore, investigating its regulatory mechanisms is important to our understanding of the physiology of fluid and electrolyte balance. Because essentially all of the regulatory sites on the channel are on the intracellular surface, patch clamp methods have proven extremely useful in the electrophysiological characterization of the sodium channel by isolating it from other channel proteins in the epithelial membrane and by allowing access to the intracellular surface of the protein. We have examined three different regulatory mechanisms. (1) Inhibition of channel activity by activation of protein kinase C; (2) activation of the channel by agents which activate G-proteins; and (3) modulation of channel kinetics and channel number by mineralocorticoids. Activation of protein kinase C by phorbol esters or synthetic diacylglycerols reduces the open probability of sodium channels. Protein kinase C can be activated in a physiological context by enhancing apical sodium entry. Actions which reduce sodium entry (low luminal sodium concentrations or the apical application of amiloride) increase channel open probability. The link between sodium entry and activation of protein kinase C appears to be mediated by intracellular calcium activity linked to sodium via a sodium/calcium exchange system. Thus, the intracellular sodium concentration is coupled to sodium entry in a negative feedback loop which promotes constant total entry of sodium. Activation of G-proteins by pertussis toxin greatly increases the open probability of sodium channels. Since channels can also be activated by pertussis toxin or GTP gamma S in excised patches, the G-protein appears to be closely linked in the apical membrane to the sodium channel protein itself. The mechanism for activation of this apical G-protein, when most hormonal and transmitter receptors are physically located on the basolateral membrane, is unclear. Mineralocorticoids such as aldosterone have at least two distinct effects. First, as expected, increasing levels of aldosterone increase the density of functional channels detectable in the apical membrane. Second, contrary to expectations, application of aldosterone increases the open probability of sodium channels. Thus aldosterone promotes the functional appearance of new sodium channels and promotes increased sodium entry through both new and pre-existant channels.
Mol Cell Biochem 1990 Dec 20
PMID:Regulation of the amiloride-blockable sodium channel from epithelial tissue. 196 46

A number of repeated sequences was identified in the chromosome of Bordetella pertussis by the electron microscopic analysis of the chromosomal DNA of this microorganism. One of the sequences was cloned on the vector plasmid pHC79. It is shown to consist of two elements RSBP1 and RSBP2. The first elements is probably identical to an RS-element described previously. The cloned RSBP1 element is shown to stimulate the deletion formation in the genome of the plasmid pMKII and is able to transpose into the chromosome of Escherichia coli. The latter properties permit one to classify RSBP1 as an element belonging to a class of migrating genetical elements.
Mol Gen Mikrobiol Virusol 1990 Dec
PMID:[Mobile element RSBP1 of Bordetella pertussis]. 196 19

Some beta-adrenergic receptor (beta AR) antagonists, in addition to blocking receptor-mediated responses, possess agonistic properties or intrinsic sympathomimetic activity (ISA). In this study we describe several techniques for amplification of cAMP levels as a measure of agonistic activity, and we apply these techniques to the study of beta AR antagonists with ISA. We show that 1) a variety of beta AR antagonists with ISA, including alprenolol and cyanopindolol, enhance cyclic AMP accumulation in S49 lymphoma cells if cells are also incubated with the diterpene forskolin; 2) beta AR blockers with ISA stimulate cAMP accumulation in the presence of a water-soluble analog of forskolin but not in the presence of 9,11-dideoxyforskolin (which does not activate adenylyl cyclase); 3) the potentiation by forskolin is not unique to S49 cells but is also observed in BC3H1 smooth muscle-derived cells; 4) stimulation of cAMP accumulation by beta-blockers with ISA occurs in S49 cells in three additional settings that do not involve the use of forskolin, after pretreatment with pertussis toxin to inactivate the inhibitory guanine nucleotide binding protein, after pretreatment with [D-Trp8]-somatostatin to sensitize adenylyl cyclase, and using a radioimmunoassay to quantitate levels of cellular cAMP. We conclude that beta AR antagonists with ISA can weakly stimulate intracellular cAMP accumulation, but this stimulation is not easily detected. Elevation of cAMP levels may account for the agonistic effects of these drugs or, at least provides a measure of stimulatory guanine nucleotide-binding protein activation by these compounds.
Mol Pharmacol 1990 Jan
PMID:Amplification of cyclic AMP generation reveals agonistic effects of certain beta-adrenergic antagonists. 196 18

Escherichia coli containing a cloned gene encoding the Bordetella pertussis serotype 2 fimbrial subunit failed to produce detectable levels of the gene product in whole-cell extracts. To engineer plasmids capable of directing the expression in E. coli of high levels of this product, both as a pre-protein and as a methionylated mature form the upstream signals of the fimbrial subunit gene were replaced by the lambda P(L) and P(R) promoters and the E. coli atpE translational initiation region. These constructs did not result in the expression of fimbrial subunit at detectable levels in several E. coli strains including DH5. However, they did in E. coli CAG629, which is lon protease and heat shock protein deficient. Both pre-protein and methionylated mature protein had molecular weights of 25.0 kD, which indicated that correct processing of the leader sequence had occurred and thus that it was transposed across the inner membrane. Electron microscopic investigation of the cell surface of E. coli cells expressing either form of the fimbrial gene failed to detect the presence of filamentous structures. The methionylated mature form of the recombinant fimbrial subunit was purified to apparent homogeneity. After dialysis in appropriate conditions it was seen to autoassemble into protein polymers. Antibodies raised against polymerized recombinant subunit reacted weakly with whole B. pertussis serotype 2 fimbriae in immunodot blot assays. However, such antibodies reacted in Western blots equally well with the recombinant and wild-type form of the fimbrial subunit.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Microbiol 1990 Jan
PMID:Engineering upstream transcriptional and translational signals of Bordetella pertussis serotype 2 fimbrial subunit protein for efficient expression in Escherichia coli: in vitro autoassembly of the expressed product into filamentous structures. 196 7

The present study was carried out to evaluate the effects of biologically active atriopeptin II (APII) in synchronously contracting monolayer cultures of rat ventricular myocytes. The effects of 10 nM APII on Ca influx, contractile behavior and cyclic nucleotide content of the cells were measured. Applied acutely APII had no effect on Ca influx. There was however a time-dependent effect such that after 30 min Ca influx (pmol/cm2/s) had declined from a control (mean +/- S.E.M.) of 1.53 +/- 0.16 to 1.02 +/- 0.07 (P less than 0.001; n = 6). There was parallel decline in both the magnitude and velocity of cell edge motion which was maximal in 30 min at which time cell edge motion measured 65.3 +/- 4.4% of control. Treatment with APII for 30 min decreased cAMP (pmol/mg protein) from 5.35 +/- 0.17 to 2.86 +/- 0.24 (P less than 0.001; n = 5). At the same time cGMP (pmol/mg protein) increased from 0.86 +/- 0.21 to 2.14 +/- 0.33 (P less than 0.001; n = 5). Further studies elucidated the fact that the decline in Ca influx and contractile behavior was dependent on the decrease in cAMP rather than the increase in cGMP. Pre-treatment of the cells with 5 ng/ml of pertussis toxin to ADP-ribosylate the Gi protein abolished the effects of APII on cAMP, Ca influx and contractile behavior. The results indicate that in myocardial cells, as in other cells, APII stimulates guanylate cyclase and inhibits adenylate cyclase. The resultant fall in cAMP decreases Ca influx and negatively influences the contractile behavior of the cells.
J Mol Cell Cardiol 1990 Feb
PMID:Effect of atriopeptin II on Ca influx, contractile behavior and cyclic nucleotide content of cultured neonatal rat myocardial cells. 196 67

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.
Mol Pharmacol 1990 May
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

D2 dopamine receptors and somatostatin receptors in adenohypophyseal cells are coupled through G proteins to various transduction mechanisms. To study the involvement of these different transduction mechanisms and of various G proteins in the dopamine and somatostatin regulation of prolactin (PRL), growth hormone (GH) and thyroid-stimulating hormone (TSH) secretions, we have pretreated the adenohypophyseal cells in primary culture with increasing doses of pertussis toxin. The guanosine triphosphate (GTP) dependency of the negative coupling of dopamine and somatostatin receptors with adenylate cyclase in the same membrane preparation from anterior pituitary cells was different. In fact, higher GTP doses were requested to obtain dopamine inhibition, suggesting that different G proteins were involved in the coupling of these two receptors with adenylate cyclase. However, the inhibition of adenylate cyclase activity by both neurohormones was fully sensitive to pertussis toxin pretreatment with a similar IC50 for the toxin. The IC50 for the toxin was also similar for the blockade of dopamine or somatostatin inhibition of the three-hormone secretion as well as for the stimulation on basal PRL or GH secretion or the reduction of thyrotropin-releasing hormone (TRH)-stimulated prolactin secretion, suggesting that the toxin acts through similar mechanisms on these different phenomena. Pretreatment of the cells with Bordetella pertussis toxin differentially affected the effects of both neurohormones on the three cell types. A complete reversion of the inhibition of secretion was observed only in the case of somatostatin on PRL and TSH cells. In contrast, the somatostatin inhibition of GH secretion was only partially reversed by the pertussis toxin pretreatment. This was also the case of dopamine inhibition of PRL secretion. It can be concluded that: (1) On PRL secretion dopamine and somatostatin do not share all the mechanisms since the intensity of their inhibition and the reversibility of their effects by pertussis toxin were differential. (2) Different mechanisms of action are implicated in the effect of somatostatin on PRL, GH and TSH secretions. (3) Different G proteins might be involved in the coupling of dopamine and somatostatin receptors with adenylate cyclase.
Mol Cell Endocrinol 1990 Oct 01
PMID:Differential coupling with pertussis toxin-sensitive G proteins of dopamine and somatostatin receptors involved in regulation of adenohypophyseal secretion. 198 65


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