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)

The properties of the adenylate cyclase from forskolin-resistant mutants of Y1 adrenocortical tumor cells was compared with the properties of the enzyme from parental Y1 cells in order to localize the site of mutation. In parental Y1 cells, forskolin stimulated adenylate cyclase activity with kinetics suggestive of an interaction at two sites; in mutant cells, forskolin resistance was characterized by a decrease in enzymatic activity at both sites. Forskolin potentiated the enzyme's responses to NaF and guanyl-5'-yl imidodiphosphate (Gpp(NH)p) in parent and mutant clones, and the mutant enzyme showed the same requirements for Mg2+ and Mn2+ as did the parent enzyme. The adenylate cyclase associated with forskolin-resistant mutants was insensitive to ACTH and was less responsive to Gpp(NH)p than was the parent enzyme. In parental Y1 cells and in the forskolin-resistant mutants, cholera toxin catalyzed the transfer of [32P]ADP-ribose from [32P]NAD+ into three membrane proteins associated with the alpha subunit of Gs; however, the amount of labeled ADP-ribose incorporated into mutant membranes was reduced by as much as 70%. Both parent and mutant membranes were labeled by pertussis toxin to the same extent. The insensitivity of the mutant adenylate cyclase to ACTH and Gpp(NH)p and the selective resistance of the mutant membranes to cholera toxin-catalyzed ADP-ribosylation suggest that a specific defect associated with Gs is involved in the mutation to forskolin resistance in Y1 cells.
 ...
PMID:Forskolin-resistant Y1 mutants harbor defects associated with the guanyl nucleotide-binding regulatory protein, Gs. 282 64

The effects of fentanyl isothiocyanate (FIT) and pertussis toxin on the binding of [3H]D-Ala2, D-Leu5-enkephalin ([3H]DADLE) to rat brain membranes were compared. The site of action of pertussis toxin was confirmed by the labeling of a 41,000 dalton protein in the presence of [alpha-32P]NAD. Both reagents produced inhibition of [3H]DADLE binding when binding was assayed in 10 mM Tris-HCl buffer alone. FIT inhibited binding 91% whereas pertussis toxin treatment resulted in 27% inhibition. However, when binding was assayed in 10 mM Tris-HCl containing SMG (100 mM NaCl, 3 mM manganese acetate, and 2 microM guanosine triphosphate), inhibition due to both reagents was attenuated markedly: 66% for FIT and 5% for toxin. In addition, both reagents markedly potentiated enhancement of binding by SMG. Thus, the effects of FIT and pertussis toxin on [3H]DADLE binding were qualitatively similar. These results suggest that FIT and pertussis toxin affect binding of [3H]DADLE to the same population of delta receptors. This was further supported by the observation that treatment of membranes with FIT prior to pertussis toxin treatment blocked the effect of toxin on [3H]DADLE binding. FIT selectively eliminates the SMG-insensitive, mu-competitive [3H]DADLE binding site [Rothman et al., Neuropeptides 4, 201 (1984); Rothman et al., Molec. Pharmac. 27, 399 (1985)]. These results indicate that this site is coupled to G protein substrates for pertussis toxin and that it mediates the inhibitory effects of delta ligands on adenylate cyclase. The FIT-insensitive, SMG-sensitive mu-noncompetitive [3H]DADLE site appears not to be coupled to G protein substrates for pertussis toxin and may mediate some other biochemical effects of delta ligands.
 ...
PMID:Differential coupling of mu-competitive and mu-noncompetitive delta opiate receptors to guanine nucleotide binding proteins in rat brain membranes. 282 87

The effects of salmon calcitonin (sCT) and human calcitonin (hCT) and of rat (r) and human (h) calcitonin gene-related peptide (CGRP) on intracellular cAMP accumulation were tested in human breast cancer cells (MCF7). In addition to the well known stimulatory effect, each showed a significant inhibitory effect on cAMP accumulation at low doses. cAMP concentrations in response to sCT, hCT, and rCGRP decreased to 47 +/- 2, 45 +/- 4, and 56 +/- 2% (mean +/- 1 SE) of baseline. The potency ratios for the inhibitory action of sCT, hCT, and rCGRP (1:0.25:0.005, respectively) were similar to the potency ratios for stimulatory action (1:0.3:0.005). The inhibition of cAMP accumulation developed at 300-fold lower peptide concentrations than the stimulation. Preincubation with pertussis toxin or with manganese completely abolished the inhibitory effect of the peptides, suggesting that this is mediated by an inhibitory adenylate cyclase regulatory protein. sCT, hCT, and CGRP each showed unique patterns with regard to time course of inhibition of cAMP accumulation. We conclude that 1) CT can activate an inhibitory adenylate cyclase regulatory protein and a stimulatory adenylate cyclase regulatory protein, and 2) CT effect on an inhibitory adenylate cyclase regulatory protein in MCF 7 cells is evident at far lower hormone concentrations than its effect on a stimulatory adenylate cyclase regulatory protein.
 ...
PMID:Dual effects of calcitonin and calcitonin gene-related peptide on intracellular cyclic 3',5'-monophosphate in a human breast cancer cell line. 283 Oct 23

We have studied the influence of myocardial infection with Trypanosoma cruzi on the beta-adrenergic adenylate cyclase complex in mouse myocardial membranes. The maximal rate of cAMP generation (Vmax) and the concentration of agonist associated with 50% of the maximal activity (apparent Kact) were determined for a series of agents. Six days after infection, the Vmax for isoproterenol significantly declines without a change in the apparent Kact. After 21 days of infection, both the Vmax and apparent Kact for isoproterenol are reduced. At 6 and 21 days of infection, the affinity of the beta-receptor for [125I]iodocyanopindolol declines from 0.84 to 3.6 and 3 nM, respectively, while the receptor density increases with the duration of infection from 33 to 57 and 82 fmol/mg protein, respectively. The Vmax (but not the apparent Kact) for forskolin and Mg2+- and Mn2+-associated activities declines also after 21 days. Another adenylate cyclase activity, which was stimulated by the nonhydrolyzable guanine nucleotide Gpp(NH)p, declines in relation to the duration of infection. Inhibitors of adenylate cyclase activity were also studied. Inhibition of adenylate cyclase activity by adenosine and by Gpp(NH)p (in the presence of forskolin) declines after 21 days of infection. The results suggested that the coupling proteins Ns and Ni, which mediate stimulatory or inhibitory control of receptors to adenylate cyclase activity, might be altered by infection. As monitored by cholera toxin- and pertussis toxin-dependent ADP ribosylation of their respective substrates, which include Ns and Ni proteins, respectively, there are declines in the availability of both substrates as a result of T. cruzi infection. For infected membranes, the addition of NADP enhances the magnitude of cholera toxin-dependent ADP ribosylation and renders the magnitude of pertussis toxin-dependent ADP ribosylation equal to that observed in uninfected membranes. The results support the hypothesis that infection with T. cruzi results in profound generalized alterations of the adenylate cyclase complex at several different sites.
 ...
PMID:Myocardial adenylate cyclase activity in acute murine Chagas' disease. 283 98

In the presence of 1 microM atrial natriuretic factor (ANF) and low (0.1 mM) Mg2+ concentrations, the initial rate of binding of [3H]guanosine 5'-[beta, gamma-imido)triphosphate [( 3H]p[NH]ppG) to rat lung plasma membranes was increased twofold to threefold. ANF-dependent stimulation of the initial rate of [3H]p[NH]ppG binding was reduced at high (5 mM) Mg2+ concentrations. Preincubation of membranes with p[NH]ppG (5 min at 37 degrees C) eliminated the ANF-dependent effect on [3H]p[NH]ppG binding whereas ANF-dependent [3H]p[NH]ppG binding was unaffected by similar pretreatment with guanosine 5'-[beta-thio]diphosphate (GDP[beta S]). An increase in ANF concentration from 10 pM to 1 microM caused a 40% decrease in forskolin-stimulated or isoproterenol-stimulated adenylate cyclase activities (IC50 5 nM) in rat lung plasma membranes. GTP (100 microM) was obligatory for the ANF-dependent inhibition of adenylate cyclase, which could be completely overcome by the presence of 100 microM GDP[beta S] or the addition of 10 mM Mn2+. Reduction of Na2+ concentration from 120 mM to 20 mM had the same effect. Pertussis toxin eliminated ANF-dependent inhibition of adenylate cyclase by catalyzing ADP-ribosylation of membrane-bound Ni protein (41-kDa alpha subunit of the inhibitory guanyl-nucleotide-binding protein of adenylate cyclase). The data support the notion that one of the ANF receptors in rat lung plasma membranes is negatively coupled to a hormone-sensitive adenylate cyclase complex via the GTP-binding Ni protein.
 ...
PMID:Involvement of Ni protein in the functional coupling of the atrial natriuretic factor (ANF) receptor to adenylate cyclase in rat lung plasma membranes. 283 33

Earlier, we demonstrated that agonist binding to synaptic plasma membranes involves a multi-step association process. In this study, high affinity binding kinetics of an agonist, [3H]D-Ala2-D-Leu5-enkephalin (DADLE), to delta sites on bovine hippocampal microsomal and synaptic plasma membranes (SPM) were compared. delta site selectivity of DADLE was ensured by suppressing undesirable mu site binding with 20 nM unlabeled D-Ala2-MePhe4-Glyol5-enkephalin. The kinetics of receptor binding to microsomal delta sites are generally more rapid than those of SPMs. Furthermore, the association time-dependent rate of dissociation, which is readily observed with SPMs, was not detected for microsomal binding sites. Although the apparent KD of DADLE did not differ significantly from that in SPMs, kinetic analysis indicated that little or no formation of the high affinity, slowly dissociating, complex occurred with microsomes. The absence of this complex, shown previously in SPMs to be most sensitive to guanine nucleotides, appeared to account for the attenuated effect of guanyl 5'-yl-imidodiphosphate [Gpp(NH)p] on dissociation from microsomes. Nevertheless, the presence in microsomes of inhibitory guanine nucleotide binding proteins was demonstrated by specific 32P-labeling by pertussis toxin of bands at 39 and 41 kDa, attributable to the alpha subunit of Go and Gi, respectively. The action of 100 mM Na+ to increase the off-rate is similar for both preparations. In contrast, addition of Mn2+ reduced the rates of association and dissociation for both subcellular fractions. The off-rate in the presence of Mn2+ is similar for SPMs and microsomes, displaying association time-dependent rates of dissociation for both. To determine whether Mn2+ promotes coupling in microsomes, the effect of Gpp(NH)p was examined. After a 60-min association, Gpp(NH)p did not affect microsomal kinetics but increased the off-rate from SPMs. The actions of both Na+ and Mn2+ appear to be mediated at early steps in the association process.
 ...
PMID:Binding kinetics of delta opioid receptors differ for microsomal and synaptic sites. 283 62

12-O-Tetradecanoylphorbol-13-acetate (TPA) enhances the apparent maximal velocity of adenylate cyclase in S49 lymphoma cells, an effect that seems not to result from an increased rate of activation of the catalytic subunit by the stimulatory GTP-binding protein (Gs) (Bell, J. D., Buxton, I. L. O., and Brunton, L. L. (1985) J. Biol. Chem. 260, 2625-2628). In membranes from wild type S49 cells, this enhancing effect of TPA is largely GTP-dependent; TPA enhances forskolin-stimulated adenylate cyclase activity by 35% in the presence of guanine nucleotide but only slightly (approximately 10%) in its absence. TPA causes comparable results in membranes from the cyc- variant that lacks the GTP-binding subunit of Gs. Blockade of the activity of the inhibitory GTP-binding protein (Gi) by high concentrations of Mg2+ (100 mM) or Mn2+ (3 mM) abolishes the effect of TPA to enhance adenylate cyclase activity in wild type membranes. The potentiation by TPA of cAMP accumulation in intact cells is greater than and not additive with the similar effect of pertussis toxin (an agent known to abolish hormonal inhibition of adenylate cyclase). Kinetic experiments indicate that TPA decreases the rate of activation of Gi by guanine nucleotide. We conclude that the resultant withdrawal of tonic inhibition of adenylate cyclase is one mechanism by which phorbol esters enhance guanine nucleotide-dependent cAMP synthesis.
 ...
PMID:Enhancement of adenylate cyclase activity in S49 lymphoma cells by phorbol esters. Withdrawal of GTP-dependent inhibition. 287 69

Alterations in receptor-independent activation of adenylate cyclase during proliferation and differentiation of L6E9 myoblasts were studied using Mn2+, forskolin, and Gpp(NH)p. Analyses were performed 3, 6, and 10 days following subculture, corresponding to onset of proliferation, end of proliferation with start of differentiation, and completion of differentiation, respectively. The apparent activation constant for Mn2+ decreases with the age of the culture; the apparent activation constant for Mg2+ does not. Bimodal activation by Mn2+, i.e., at concentrations greater than 10 mM, results in total adenylate cyclase activity less than the Vmax and occurs exclusively in differentiated cultures. Independent of the presence of Mg2+, forskolin activation occurs with low-and high-affinity constants in differentiated cultures and with a low affinity constant in youngest cultures; intermediate cultures (day 6) demonstrate low- and high-affinity activation only in the presence of high Mg2+. In contrast, the Vmax for forskolin increases with increasing Mg2+ in all culture ages. Although Gpp(NH)p-dependent adenylate cyclase activation occurs with an apparent activation constant independent of culture age and Mg2+, low Mg2+ fosters bimodal activation by Gpp(NH)p, i.e., above 100 microM nucleotide, total adenylate cyclase activity is less than the Vmax. The loss of stimulatory capacity by high Gpp(NH)p is greatest in differentiated cultures. Additional experiments are presented to substantiate that bimodal activation by Gpp(NH)p is specific. Cholera- and pertussis toxin-dependent ADP ribosylation patterns demonstrate a marked decrease in both Ns and Ni in differentiated cultures. The data suggest that alterations in postreceptor activation of adenylate cyclase during the course of differentiation and proliferation are mediated by guanine nucleotide binding proteins as well as by allosteric cation regulatory units.
 ...
PMID:Modifications of the adenylate cyclase complex during differentiation of cultured myoblasts. 308 96

The interaction of nucleotides with pertussis toxin (PT), and their effects on the ability of the toxin to ADP-ribosylate pure Ni, were evaluated. [32P]ATP (10 nM) bound directly to dithiothreitol-activated PT. This binding was competitively inhibited by nucleotides and anions with the following IC50 concentrations in order of decreasing potency: ATP = ATP gamma S (adenosine-5'-O-(3-thiotriphosphate)) = 0.2-0.3 microM, GDP beta S (guanosine-5'-O-(2-thiodiphosphate)) = 2-3 microM, GTP gamma S (guanosine-5'-O-(3-thiotriphosphate)) = 10-15 microM, ADP = 20-25 microM, GTP = 30-40 microM, GMP-P(NH)P (guanyl-5'-yl imidodiphosphate) = 100-150 microM, GDP = 150-200 microM, Pi = SO4(2-) = 20 mM and Cl- = acetate = 30-35 mM. Treatment of PT with ATP, AMP-P(NH)P, GTP, GDP, or GDP beta S, resulted in a stimulated state of NAD+-Ni ADP-ribosyltransferase activity. Addition of ATP, AMP-P(NH)P (adenyl-5'-yl imidodiphosphate), GTP, GDP, and GDP beta S to the ADP-ribosylation reactions resulted in increased rates of ADP-ribosyl-Ni formation. It is concluded that these effects on the nucleotides are due to their action to stimulate the activity of PT. At concentrations of PT between 0.04 and 0.4 microgram/ml, the stimulation of ADP-ribosylation of Ni effected by nucleotides was hysteretic in nature, exhibiting an approximately 25-min long lag when GDP was used as the activating nucleotide. These lags decreased with increasing concentrations of PT, and were abolished by pretreatment of the toxin with GDP or ATP. Preliminary incubation of Ni with GDP had no effect on the lag in its ADP-ribosylation by non-nucleotide treated PT. Addition of divalent cations (Mg2+, Mn2+, and Ca2+) inhibited formation of ADP-ribosyl-Ni, possibly by causing aggregation and denaturation of Ni. This is the first demonstration that both adenine and guanine nucleotides interact directly with PT and act to stimulate its activity to ADP-ribosylate Ni, and that guanine nucleotides do so regardless of whether they are nucleoside di- or triphosphates.
 ...
PMID:The interaction of nucleotides with pertussis toxin. Direct evidence for a nucleotide binding site on the toxin regulating the rate of ADP-ribosylation of Ni, the inhibitory regulatory component of adenylyl cyclase. 309 44

A variety of pharmacological agents were used as experimental probes to determine with greater precision the site(s) of damage to cerebral adenylate cyclase as a consequence of postischemic reperfusion in the gerbil. A paradigm of 60-min bilateral ischemia followed by 40-min reperfusion results in a decreased sensitivity of the catalytic site of adenylate cyclase to Mn2+. Likewise, the GTP-transducer site (guanine nucleotide regulatory or G protein) revealed depressed responses to GTP in the absence or presence of norepinephrine, dopamine agonists, substance P, yohimbine, and cholera and pertussis toxins. Moreover, a crude preparation of GTPase disclosed that damage elicited by postischemic reperfusion was directed to the higher-affinity form of this enzyme, which is associated with the overall function of the guanine nucleotide regulatory protein. Injury to adenylate cyclase was unrelated either to the ability of adrenergic ligands to bind to associated receptor sites or to the capacity of the brain to generate visual evoked potentials in response to visual stimuli.
 ...
PMID:Further probes into the molecular sites of damage to cerebral adenylate cyclase following postischemic reperfusion. 310 40


<< Previous 1 2 3 4 5 6 7 8 9 Next >>