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)

Myristate is a fatty acid (fourteen-carbon chain with no double bonds, C14:0) linked to the amino-terminal glycine of several proteins, including alpha-subunits of heterotrimeric (alpha/beta gamma) G proteins. We report here a novel modification at the N terminus of the alpha-subunit of the photoreceptor G protein transducin, T alpha, with heterogeneous fatty acids composed of laurate (C12:0), unsaturated C14:2 and C14:1 fatty acids, and a small amount (approximately 5%) of myristate. Both the GTPase activity of T alpha/T beta gamma and the T beta gamma-dependent ADP-ribosylation of T alpha catalysed by pertussis toxin were inhibited by the lauroylated and myristoylated N-terminal peptide of T alpha. The myristoylated peptide gave 50% inhibition at a 3.5 to approximately 4.5-fold lower concentration than the lauroylated peptide in each assay, indicating that the strength of the interaction between T alpha and T beta gamma is altered by heterogeneous fatty acids linked to T alpha. This suggests that a looser subunit interaction in transducin which is due to an abundance of N-linked fatty acids other than myristate would favour the rapid turnover and catalysis essential for the visual excitation in photoreceptor cells.
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PMID:Lipid modification at the N terminus of photoreceptor G-protein alpha-subunit. 143 26

A guanosine 5'-[gamma-[35S]thio]triphosphate-binding activity was detergent-extracted from Trypanosoma cruzi membranes. This binding activity was co-eluted from gel-filtration columns with a factor which, in a heterologous reconstitution system, blocks glucagon stimulation of adenylate cyclase activity in liver membranes. ADP-ribosylation of these membranes by pertussis toxin eliminated this blocking capacity. Incubation of T. cruzi membranes with activated pertussis toxin and [adenylate-32P]NAD+ led to the incorporation of radioactivity into a labelled product with an apparent M(r) of approx. 43,000. Crude membranes were electrophoresed on SDS/polyacrylamide gels and analysed, by Western blotting, with GA/1 anti-alpha common, AS/7 anti-alpha t, anti-alpha i1 and anti-alpha i2 polyclonal antibodies. These procedures led to the identification of a specific polypeptide band of about 43 kDa. Another polypeptide reacting with the SW/1 anti-beta antibody, of about 30 kDa, was also detected in the membrane fraction.
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PMID:Characterization of a Gi-protein from Trypanosoma cruzi epimastigote membranes. 144 3

Photoaffinity labelling by a GTP analogue has been used to identify a 42 kDa band as the major G alpha subunit in squid photoreceptor membranes, recently identified by partial sequence analysis to be a member of the Gq sub-group of GTP-binding proteins [Pottinger, Ryba, Keen & Findlay (1991) Biochem. J. 279, 323-326]. Guanine-nucleotide-binding displacement analysis gave a stoichiometry of 1 G-protein per 12.5 rhodopsin molecules, the same as in vertebrate rod photoreceptors. Binding was not detected above background in the dark, but was rapidly activated by light. Unlike vertebrate transducin, this G-protein is very temperature-sensitive. GTP binding is maximal at temperatures less than 10 degrees C and is much decreased after several minutes above 18 degrees C. The light-stimulated GTPase rate is maximal around 10 degrees C, above which the loss of binding sites counteracts the increase in hydrolytic rate per site. Earlier studies described light-sensitive G alpha components of 40 and 45 kDa, by ADP-ribosylation in the presence of cholera and pertussis toxins. These are now shown to be very minor components, as the prolonged treatment at elevated temperature required for ADP-ribosylation is sufficient to inactivate the major G alpha totally. Unlike the minor G alpha components, the 42 kDa G alpha is not inhibited by Ca2+.
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PMID:Activation of the GTP-binding protein Gq by rhodopsin in squid photoreceptors. 144 12

We have previously shown that the stimulatory effects of guanine nucleotides, N-ethylcarboxamide-adenosine and other agonists on adenylate cyclase activity were diminished in aorta and heart sarcolemma of spontaneously hypertensive rats (SHR) [Anand-Srivastava (1988) Biochem. Pharmacol. 37, 3017-3022]. In the present studies, we have examined whether the decreased response of these agonists is due to the defective GTP-binding proteins (G-proteins) which couple the receptors to adenylate cyclase, and have therefore measured the levels of G-proteins in aorta and heart from SHR and their respective Wistar-Kyoto (WKY) controls by using pertussis toxin (PT)- and cholera toxin (CT)-catalysed ADP-ribosylations and immunoblotting techniques using specific antibodies against G-proteins. The labelling with [32P]NAD+ and PT identified a 40/41 kDa protein in heart and aorta from WKY and SHR and was significantly increased in the hearts (approximately 100%) and aorta (approximately 30-40%), from SHR as compared with WKY. Immunoblotting revealed an increase in the levels of the G-protein alpha-subunits Gi alpha-2 and Gi alpha-3 in heart and Gi alpha-2 in aorta, whereas no change in Go alpha was observed in heart from SHR and WKY. On the other hand, no differences were observed in CT labelling or immunoblotting of stimulatory G-protein (Gs) in heart and aorta from WKY and SHR. In addition, CT stimulated the adenylate cyclase activity in heart sarcolemma from WKY and SHR to a similar extent. These results were correlated with adenylate cyclase inhibition and stimulation by various hormones. Angiotensin II (AII), atrial natriuretic factor (ANF) and oxotremorine-mediated inhibition was found to be greater in SHR as compared with WKY, whereas the stimulatory effects of adrenaline, isoprenaline, dopamine and forskolin were diminished in SHR aorta as compared to WKY. These results indicate that regulatory protein G(i) is more expressed in SHR, which may be associated with the decreased responsiveness of stimulatory hormones and increased sensitivity of inhibitory hormones to stimulate/inhibit adenylate cyclase activity. It may thus be suggested that the enhanced G(i) activity may be one of the mechanisms responsible for the diminished vascular tone and impaired myocardial functions in hypertension.
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PMID:Enhanced expression of inhibitory guanine nucleotide regulatory protein in spontaneously hypertensive rats. Relationship to adenylate cyclase inhibition. 144 83

ADP-ribosylation is a posttranslational modification of proteins by amino acid-specific ADP-ribosyltransferases. Both pertussis toxin and eukaryotic enzymes ADP-ribosylate cysteine residues in proteins and also, it has been suggested, free cysteine. Analysis of the reaction mechanisms of cysteine-specific ADP-ribosyltransferases revealed that free ADP-ribose combined nonenzymatically with cysteine. L- and D-cysteine, L-cysteine methyl ester, and cysteamine reacted with ADP-ribose, but alanine, serine, lysine, arginine, N-acetyl-L-cysteine, 2-mercaptoethanol, dithiothreitol, and glutathione did not. The 1H NMR spectrum of the product, along with the requirement for both free sulfhydryl and amino groups of cysteine, suggested that the reaction produced a thiazolidine linkage. ADP-ribosylthiazolidine was labile to hydroxylamine and mercuric ion, unlike the ADP-ribosylcysteine formed by pertussis toxin and NAD in guanine nucleotide-binding (G-) proteins, which is labile to mercuric ion but stable in hydroxylamine. In the absence of G-proteins but in the presence of NAD and cysteine, pertussis toxin generated a hydroxylamine-sensitive product, suggesting that a free ADP-ribose intermediate, expected to be formed by the NADase activity of the toxin, reacted with cysteine. Chemical analysis, or the use of alternative thiol acceptors lacking a free amine, is necessary to distinguish the enzymatic formation of ADP-ribosylcysteine from nonenzymatic formation of ADP-ribosylthiazolidine, thereby differentiating putative NAD:cysteine ADP-ribosyltransferases from NAD glycohydrolases.
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PMID:Amino acid-specific ADP-ribosylation: structural characterization and chemical differentiation of ADP-ribose-cysteine adducts formed nonenzymatically and in a pertussis toxin-catalyzed reaction. 144 18

We have previously suggested that at least two different G-proteins are involved in mediating insulin receptor functions. Here we identify and partially purify two G-proteins with apparent molecular masses of 41 and 67 kilodaltons (kDa) that interact with insulin receptors in rat adipocytes and human placenta. Treatment of isolated rat adipocytes with insulin inhibited pertussis toxin-catalyzed ADP-ribosylation of a 41-kDa G-protein in subsequently isolated plasma membranes by 30.2 +/- 3.0% and in partially purified insulin receptor preparations by 35.6 +/- 5.7%. There was no associated decrease in the concentration of the 41-kDa G-protein in the plasma membranes, as determined by immunoblot with a common G alpha antibody. The common G alpha antibody also recognized a 67-kDa protein in the plasma membranes, the concentration of which was not affected by insulin. However, the 67-kDa protein was enriched in partially purified solubilized insulin receptor preparations. Two similar, 41- and 67-kDa G-proteins were identified in the wheat germ-purified insulin receptor preparations obtained from human placenta. Removal of these two G-proteins from insulin receptor preparations results in loss of the ability of insulin to stimulate receptor kinase activity. Addition of a fraction enriched with 41- and 67-kDa G-proteins to the G-protein-depleted insulin receptor restores the insulin sensitivity of the insulin receptor kinase activity. Furthermore, addition of G-protein-depleted insulin receptors to the fraction containing partially purified 41- and 67-kDa G-proteins enhances pertussis toxin-catalyzed ADP-ribosylation of the 41-kDa G-protein. These results indicate that either the 41- or 67-kDa G-protein, or both, interact with the insulin receptor mediating insulin receptor kinase activity. Such mutual interaction and regulation between the insulin receptor and G-proteins could be an important component of the signal transduction mechanism for insulin.
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PMID:Identification, partial purification, and characterization of two guanosine triphosphate-binding proteins associated with insulin receptors. 144 23

We have studied the expression of the gene fragments encoding the enzymatically active portion of three bacterial cytotoxins: exotoxin A (ETA) of Pseudomonas aeruginosa, and pertussis toxin (PT) and adenylate cyclase toxin (CYA) of Bordetella pertussis, in sensitive mammalian target cells. Expression of active ETA and CYA was lethal to the producing cells and stable transfectants of Cos-1 cells containing the corresponding genes could not be obtained. The expression of the PTS1 subunit was tolerated by the producing mammalian cells. Since PT is cytotoxic because of ADP-ribosylation of G-proteins, we assume that the endogenously expressed PTS1 may not find the cellular target G proteins or PTS1 alone may not be sufficient for ADP-ribosylation of these proteins in vivo.
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PMID:Expression of bacterial cytotoxin genes in mammalian target cells. 144 74

To determine whether direct stimulation of endothelial G-proteins causes relaxations of the underlying vascular smooth muscle, the effects of guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and sodium fluoride were studied in porcine coronary arteries and endothelial cells. Isometric tension was measured in coronary rings contracted with prostaglandin F2 alpha. GTP gamma S (in the presence of saponin) and sodium fluoride (in the presence of AlCl3) relaxed rings with, but not those without endothelium. The responses were inhibited by nitro-L-arginine and pertussis toxin. In membrane fractions of coronary endothelial cells, GTP gamma S and sodium fluoride inhibited the ADP-ribosylation of G-proteins catalyzed with [32P]-NAD and pertussis toxin. These data suggest that direct stimulation of G-proteins in endothelial cells by GTP gamma S and sodium fluoride causes a pertussis toxin-sensitive relaxation which may be attributed to the release of nitric oxide.
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PMID:Guanosine 5'-O-(3-thiotriphosphate) causes endothelium-dependent, pertussis toxin-sensitive relaxations in porcine coronary arteries. 144 86

A guanine nucleotide regulatory protein (G-protein) was purified to homogeneity from rat brain membrane though a series of chromatography runs, including DE-52 ion exchange, AcA-34 ultrogel, and octyl-Sepharose columns. The purified G-protein consisted of 3 subunits with molecular weights of 41000, 36000, and 8000, respectively. The alpha-subunit of the G-protein possessed high affinity GTP binding sites (k = 22.5 nmol/L) and GTPase activity (Km = 82.5 nmol/L, Vmax = 2.8 pmol/min/microgram protein), and it could be ADP-ribosylated by [adenylate-32P]-NAD in the presence of pertussis toxin. These results suggest that the purified protein was Gi-protein.
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PMID:The purification of a guanine nucleotide regulatory protein from rat brain membrane and the measurement of its GTPase. 145 Mar 95

The role of heterotrimeric G-proteins on the formation of constitutive secretory vesicles (CSVs) and immature secretory granules (ISGs) from the trans-Golgi network (TGN) of PC12 cells was investigated. Using immunofluorescence and subcellular fractionation in conjunction with immunoblotting or ADP-ribosylation by either pertussis toxin or cholera toxin, TGN membranes were found to contain not only several alpha i/alpha o G-protein subunits including apparently alpha i3, but also alpha s. Pertussis toxin treatment of cells, which resulted in the stoichiometric ADP-ribosylation of alpha i/alpha o, a modification known to prevent their coupling to receptors, led to the stimulation of cell-free CSV and ISG formation, suggesting the presence of a guanine nucleotide exchange factor for alpha i/alpha o on the TGN. Mastoparan-7, a peptide known to mimic an activated receptor and to stimulate nucleotide exchange on alpha i/alpha o, inhibited cell-free vesicle formation, an effect abolished by pertussis toxin. In contrast, activation of alpha s by cholera toxin treatment of cells resulted in a stimulation of cell-free CSV and ISG formation. This stimulation could be reversed when the alpha subunits not activated by cholera toxin, i.e. alpha i/alpha o, were activated by GTP gamma S and [AIF4]-. Our results show that both inhibitory and stimulatory trimeric G-proteins on the TGN participate in the regulation of secretory vesicle formation.
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PMID:Multiple trimeric G-proteins on the trans-Golgi network exert stimulatory and inhibitory effects on secretory vesicle formation. 146 9


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