Soluble guanine nucleotide-dependent ADP-ribosylation factors in activation of adenylyl cyclase by cholera toxin.
Explore the source record for details and available documents.
ADP-Ribosylation Factors↗
Biomedical subjects
J Moss
Publications and source records attributed to J Moss.
Effects of fenoldopam on renal blood flow and systemic hemodynamics during isoflurane anesthesia.
The authors compared the systemic hemodynamic and renal vascular effects of hypotension induced by fenoldopam with those produced by the most commonly used hypotensive agent, sodium nitroprusside, in 10 dogs. Mean arterial pressure decreased 26% +/- 3% from control following infusion with fenoldopam, and 30% +/- 2% following infusion with sodium nitroprusside (these decreases were not significantly different between the groups). Renal blood flow (RBF) was preserved during fenoldopam-induced hypotension (214 +/- 16 mL/min at baseline and 197 +/- 16 mL/min after fenoldopam-induced hypotension). In contrast, RBF decreased from 223 +/- 17 mL/min to 167 +/- 12 mL/min during sodium nitroprusside-induced hypotension (P less than 0.02). The differences in RBF between the two groups occurred in spite of the fact that cardiac output and pulmonary capillary wedge pressure were kept similar between the two groups. The authors conclude that fenoldopam, a selective dopamine1 (DA1) receptor agonist, preserves blood flow to the kidney during induced hypotension. On the other hand, sodium nitroprusside is a nonselective arteriolar and venous vasodilator that redistributes blood flow away from the kidneys during induced hypotension.
2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
Activation of cholera toxin and Escherichia coli heat-labile enterotoxins by ADP-ribosylation factors, a family of 20 kDa guanine nucleotide-binding proteins.
Cholera toxin and Escherichia coli heat-labile enterotoxins are responsible, in part, for the symptomatology of cholera and traveller's diarrhoea, respectively. Effects of the toxins result from ADP-ribosylation of regulatory guanine nucleotide-binding (G) proteins; the ADP-ribosylated G protein is stabilized in an activated state, resulting in prolonged effects on its target. Toxin-catalysed ADP-ribosylation is stimulated in vitro by a family of guanine nucleotide-binding proteins, c. 20 kDa, termed ADP-ribosylation factors or ARFs. In the presence of GTP, but not GDP or adenine analogues, ARFs serve as allosteric activators of the toxin. The effects are amplified by certain phospholipids and detergents which promote guanine nucleotide binding. Six different mammalian ARF genes have been identified. They encode highly conserved, ubiquitous proteins of 175 to 181 amino acids, containing consensus domains responsible for guanine nucleotide binding. Differences in amino acid sequences are localized near the amino terminus and in the carboxy half of the protein. Although the physiological functions of ARFs have not been precisely defined, their immunological localization to the Golgi is consistent with a role in the regulated orderly movement of newly synthesized proteins from the endoplasmic reticulum, through the Golgi system to their ultimate destination.
ADP-Ribosylation Factors↗
Different forms of Go alpha mRNA arise by alternative splicing of transcripts from a single gene on human chromosome 16.
Go alpha, (gene symbol GNA01), a member of the signal-transducing guanine nucleotide-binding (G) protein family, has been implicated in ion channel regulation. Some tissues contain multiple Go alpha mRNAs of different sizes that differ in the 3' untranslated regions (UTRs). Using sequence-specific 48-base oligonucleotides, two complementary to the different 3' UTRs and one complementary to the coding region, we investigated the origin of the multiple Go alpha transcripts, the organization of the Go alpha gene, the interspecies conservation of 3' UTRs, and the chromosomal localization of Go alpha. Oligonucleotides labeled to high specific activity by using terminal deoxynucleotidyltransferase each hybridized with a single band of restriction enzyme-digested mouse and human DNAs. In three of four digests of human DNA, the two probes specific for the different 3' UTRs hybridized with the same restriction fragment. Thus, these nucleotide sequences are in close proximity in the human genome. The order of the UTRs in the bovine, human, and mouse genomes was confirmed directly by polymerase chain reaction (PCR) amplification and sequencing. Hybridization of bovine oligonucleotide sequence with mouse and human genomic DNA indicated a high degree of interspecies sequence conservation: conservation was confirmed by PCR amplification and sequencing. Bands detected by both UTR probes, as well as the predominant bands detected by a bovine Go alpha cDNA, segregated with human chromosome 16 on Southern blot analysis of human-mouse somatic cell hybrids. We conclude that Go alpha mRNAs with different 3' UTRs arise by alternative splicing of transcripts from a single gene. The UTRs, which exhibit a high degree of interspecies conservation, may play a role in regulation of Go alpha expression during differentiation or in specific tissues. The use of oligonucleotide probes of the type described here represents a new strategy, potentially widely applicable for mapping and elucidating structural features of genes.
Animals↗
Binding sites of the 9- and 14-kilodalton heterodimeric protein subunit of the signal recognition particle (SRP) are contained exclusively in the Alu domain of SRP RNA and contain a sequence motif that is conserved in evolution.
The mammalian signal recognition particle (SRP) is a small cytoplasmic ribonucleoprotein required for the cotranslational targeting of secretory proteins to the endoplasmic reticulum membrane. The heterodimeric protein subunit SRP9/14 was previously shown to be essential for SRP to cause pausing in the elongation of secretory protein translation. RNase protection and filter binding experiments have shown that binding of SRP9/14 to SRP RNA depends solely on sequences located in a domain of SRP RNA that is strongly homologous to the Alu family of repetitive DNA sequences. In addition, the use of hydroxyl radicals, as RNA-cleaving reagents, has revealed four distinct regions in this domain that are in close contact with SRP9/14. Surprisingly, the nucleotide sequence in one of these contact sites, predicted to be mostly single stranded, was found to be extremely conserved in SRP RNAs of evolutionarily distant organisms ranging from eubacteria and archaebacteria to yeasts and higher eucaryotic cells. This finding suggests that SRP9/14 homologs may also exist in these organisms, where they possibly contribute to the regulation of protein synthesis similar to that observed for mammalian SRP in vitro.
Animals↗
Activation of Escherichia coli heat-labile enterotoxins by native and recombinant adenosine diphosphate-ribosylation factors, 20-kD guanine nucleotide-binding proteins.
Escherichia coli heat-labile enterotoxins (LT) are responsible in part for "traveler's diarrhea" and related diarrheal illnesses. The family of LTs comprises two serogroups termed LT-I and LT-II; each serogroup includes two or more antigenic variants. The effects of LTs result from ADP ribosylation of Gs alpha, a stimulatory component of adenylyl cyclase; the mechanism of action is identical to that of cholera toxin (CT). The ADP-ribosyltransferase activity of CT is enhanced by 20-kD guanine nucleotide-binding proteins, known as ADP-ribosylation factors or ARFs. These proteins directly activate the CTA1 catalytic unit and stimulate its ADP ribosylation of Gs alpha, other proteins, and simple guanidino compounds (e.g., agmatine). Because of the similarities between CT and LTs, we investigated the effects of purified bovine brain ARF and a recombinant form of bovine ARF synthesized in Escherichia coli on LT activity. ARF enhanced the LT-I-, LT-IIa-, and LT-IIb-catalyzed ADP ribosylation of agmatine, as well as the auto-ADP ribosylation of the toxin catalytic unit. Stimulation of ADP-ribosylagmatine formation by LTs and CT in the presence of ARF was GTP dependent and enhanced by sodium dodecyl sulfate. With agmatine as substrate, LT-IIa and LT-IIb exhibited less than 1% the activity of CT and LT-Ih. CT and LTs catalyzed ADP-ribosyl-Gs alpha formation in a reaction dependent on ARF, GTP, and dimyristoyl phosphatidylcholine/cholate. With Gs alpha as substrate, the ADP-ribosyltransferase activities of the toxins were similar, although CT and LT-Ih appeared to be slightly more active than LT-IIa and LT-IIb. Thus, LT-IIa and LT-IIb appear to differ somewhat from CT and LT-Ih in substrate specificity. Responsiveness to stimulation by ARF, GTP, and phospholipid/detergent as well as the specificity of ADP-ribosyltransferase activity are functions of LTs from serogroups LT-I and LT-II that are shared with CT.
ADP-Ribosylation Factors↗
Contact-dependent transfer of a lysosomal enzyme from lymphocytes to fibroblasts.
In this study we have examined the mechanism underlying the contact-mediated transfer of a lysosomal enzyme from lymphocytes to fibroblasts in culture. We found that although antibody against the mannose 6-phosphate lysosomal targetting receptor (MPR) completely inhibited fibroblast uptake of the lysosomal enzyme beta-glucuronidase (Gus) from the culture medium, it had no effect on the transfer of the enzyme from normal lymphocytes. In contrast, the presence of antibody that prevented the adhesion of the lymphocytes to the fibroblasts inhibited Gus acquisition but had no effect on endocytosis. Immunogold electron microscopy of the contact site between the two types of cell showed that the transfer of Gus involved uncoated vesicles localized near the cell surface of the fibroblast at sites of contact with the lymphocytes. The acquired lymphocyte enzyme was shown to be transported to the fibroblast lysosomes.
Animals↗
GTP-binding protein G alpha Z: its down-regulation by dexamethasone and its credentials as a mediator of antigen-induced responses in RBL-2H3 cells.
We have investigated the possible role of guanine nucleotide-binding proteins in the process of antigen-induced exocytosis in a cultured rat mast cell line, RBL-2H3 cells. The mRNAs for the alpha subunits of the guanine nucleotide-binding proteins G alpha S (short and long forms), G alpha i-2, G alpha i-3, and G alpha Z were detected by hybridization with G alpha-specific oligonucleotide probes. The corresponding proteins were identified in membranes of RBL-2H3 cells on the basis of size, immunoreactivity with specific antibodies, and their ability to serve as substrates for ADP-ribosylation by cholera toxin or pertussis toxin. Treatment of cells with as little as 10(-9) to 10(-7) M dexamethasone markedly decreased the amount of G alpha Z mRNA and membrane G alpha Z, as well as the responsiveness of the cells to antigen stimulation. In the same cells, the exposure to dexamethasone caused an increase in the amounts of certain other G alpha subunits, particularly G alpha i-3, and in the responsiveness of the cells to an adenosine analog, N(ethylcarboxamido)-adenosine. Because of the apparent decrease in G alpha Z mRNA and protein in dexamethasone-treated cells and the fact that neither cholera toxin nor pertussis toxin inhibits the stimulatory signals to antigen [J. Biol. Chem. 265:745-753 (1990)], we suggest that G alpha Z is a potential candidate for regulating the early signals in antigen-stimulated RBL-2H3 cells.
Adenosine Diphosphate↗
Influence of the site of tumor growth on the capacity of a low tumorigenic line of Friend erythroleukemia cells to differentiate.
Friend erythroleukemia cells (FLC) passaged in mice are highly tumorigenic and multiply extensively in the livers of suckling DBA/2 mice without differentiating. In contrast, in vitro passaged FLCs injected intravenously were of low tumorigenicity, multiplied to a limited extent in the livers of suckling mice, and underwent marked differentiation from the proerythroblast to the orthochromatic erythroblast stage in the liver. The presence of characteristic C-type virions budding from the cell surface in various stages of erythroid differentiation served as a marker of the injected FLCs. When the same in vitro passaged FLCs that differentiated in the liver were injected subcutaneously in suckling mice, they formed large subcutaneous tumors consisting of sheets of undifferentiated tumor cells. It is concluded that the tumorigenicity of FLCs depended on the site of tumor growth and that there is an inverse correlation between the tumorigenic capacity and the capacity to differentiate.
Animals↗
Inactivation of bacterial glutamine synthetase by ADP-ribosylation.
Glutamine synthetase from Escherichia coli was inactivated by chemical modification with arginine-specific reagents (Colanduoni, J. A., and Villafranca, J. J. (1985) Biochem. Biophys. Res. Commun. 126, 412-418). E. coli glutamine synthetase was also a substrate for an erythrocyte NAD:arginine ADP-ribosyltransferase. Transfer of one ADP-ribosyl group/subunit of glutamine synthetase caused loss of both biosynthetic and gamma-glutamyltransferase activity. The ADP-ribose moiety was enzymatically removed by an erythrocyte ADP-ribosylarginine hydrolase, resulting in return of function. The site of ADP-ribosylation was arginine 172, determined by isolation of the ADP-ribosylated tryptic peptide. Arginine 172 lies in a central loop that extends into the core formed by the 12 subunits of the native enzyme. The central loop is important in anchoring subunits together to yield the spatial orientation required for catalytic activity. ADP-ribosylation may thus inactivate glutamine synthetase by disrupting the normal subunit alignment. Enzyme-catalyzed ADP-ribosylation may provide a simple, specific technique to probe the role of arginine residues in the structure and function of proteins.
ADP Ribose Transferases↗
Guanine nucleotide-dependent ADP-ribosylation of soluble rho catalyzed by Clostridium botulinum C3 ADP-ribosyltransferase. Isolation and characterization of a newly recognized form of rhoA.
Two C3 ADP-ribosyltransferase substrates with different characteristics were isolated from bovine brain cytosol. Amino acid sequences of tryptic peptides from the two substrates were identical to rhoA and rhoB; hence, the purified proteins are referred to as rhoA* and rhoB*, respectively. Soluble rhoA* exhibits properties different from those previously reported for rho proteins. In contrast to other C3 substrates, rhoA* behaved as a 77-80-kDa protein on gel filtration, although on sodium dodecyl sulfate-polyacrylamide gel electrophoresis the ADP-ribosylated moiety had a mobility consistent with a 21.5-kDa protein. Furthermore, C3-catalyzed ADP-ribosylation of rhoA* was dependent on guanine nucleotides in the presence of 1 mM Mg2+ or 1 mM EDTA (0.19 microM free Mg2+). Half-maximal stimulation by GTP, guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S), guanylyl-imidodiphosphate (Gpp(NH)p), and GDP was observed at 16, 20, 220, and 380 nM, respectively; guanosine 5'-O-(2-thiodiphosphate), GMP, and adenine nucleotides were ineffective. In the presence of GTP gamma S, the rate and extent of ADP-ribosylation was enhanced by dimyristoylphosphatidylcholine and/or cholate. This increase in ADP-ribosylation was specific for rhoA*; it was not observed with rhoB* and has not been reported for other C3 substrates. These distinct properties suggest that rhoA* is a newly recognized type of C3 substrate, differing from the rhoA-like proteins previously reported. rhoB*, on the other hand, has properties similar to those reported for membrane-associated rhoB and its ADP-ribosylation was independent of guanine nucleotides in the presence of 1 mM Mg2+ and not affected by dimyristoylphosphatidylcholine and/or cholate.
ADP Ribose Transferases↗
cAMP-independent effects of cholera toxin on B cell activation. I. A possible role for cell surface ganglioside GM1 in B cell activation.
Cholera toxin has been used as a tool to study the effects of cAMP on the activation of B cells but may have effects independent of its ability to elevate cAMP. We found five lines of evidence which suggested that cholera toxin suppressed mitogen-stimulated B cell activation through a cAMP-independent pathway. 1) Cholera toxin (1 microgram/ml) was consistently more suppressive than forskolin (100 microM) despite the induction of higher intracellular cAMP levels by forskolin. 2) Cholera toxin was more suppressive at 1 microgram/ml than at 0.1 microgram/ml despite equivalent elevations of cAMP. 3) Washing B cells following their incubation with cholera toxin reversed much of the inhibition without altering intracellular cAMP levels. 4) The A subunit of cholera toxin, which at high concentrations (10 micrograms/ml) induced levels of cAMP comparable to those induced by cholera toxin (1 and 0.1 microgram/ml), did not inhibit B cell activation. 5) cAMP derivatives at high concentrations were much less effective than was cholera toxin in suppressing B cell activation. Although the elevation of cAMP may cause a mild inhibition of B cell proliferation, we found that even a marked elevation of cAMP did not suppress B cell proliferation, unless the elevation was persistent. We did, however, observe that the degree of toxin inhibition more closely paralleled binding of the toxin to B cells than toxin stimulation of cAMP. This result raised the possibility that binding of cholera toxin to its ganglioside GM1 receptor mediated an inhibitory signal which suppressed B cell proliferation.
8-Bromo Cyclic Adenosine Monophosphate↗
Modification of plasma membrane protein cysteine residues by ADP-ribose in vivo.
Proteins can be post-translationally modified by ADP-ribose. Previously, two classes of ADP-ribosyl protein linkages have been detected in vivo which have chemical properties indistinguishable from ADP-ribosyl arginine and ADP-ribosyl glutamate or aspartate. Reported here is the detection of a third class of endogenous ADP-ribosyl protein linkage. This class is chemically indistinguishable from ADP-ribose linked to cysteine residues by a thioglycosidic bond. The distribution of ADP-ribosyl cysteine residues was studied in subcellular fractions of rat liver. Proteins modified on cysteine were detected only in the plasma membrane fraction. Pertussis toxin is known to disrupt signal transduction of ADP-ribosylation of cysteine residues of plasma membrane GTP binding proteins. The results described here raise the interesting possibility that the endogenous modification of plasma membrane protein cysteine residues may be involved in signal transduction.
Adenosine Diphosphate Ribose↗
Multiple forms of Go alpha mRNA: analysis of the 3'-untranslated regions.
Go, a guanine nucleotide binding protein found predominantly in neural tissues, interacts in vitro with rhodopsin, muscarinic, and other receptors and has been implicated in the regulation of ion channels. Despite the virtual identity of reported cDNA sequences for the alpha subunit of Go (Go alpha), multiple molecular weight forms of mRNA have been identified in tissues from all species examined. To investigate the molecular basis for the size heterogeneity of Go alpha mRNAs, four cDNA clones were isolated from the same retinal lambda gt10 cDNA library that was used earlier to isolate lambda GO9, a clone encompassing the complete coding region of Go alpha. These clones were identified as Go alpha clones based on nucleotide sequence identity with lambda GO9 in the coding region; they diverge, however, from lambda GO9 in the 3'-untranslated region 28 nucleotides past the stop codon. An oligonucleotide probe complementary to a portion of the 3'-untranslated region of lambda GO9 that differs from the newly isolated clones hybridized with 3.0- and 4.0-kb mRNAs present in bovine brain and retina whereas a similar probe for the unique region of the new clones hybridized with a 4.0-kb mRNA in both tissues and with a 2.0-kb mRNA found predominantly in retina. A similar hybridization pattern was observed when brain poly(A+) RNA from other species was hybridized with the different 3'-untranslated region probes. It appears that differences in the 3'-untranslated regions could, in part, be the basis for the observed heterogeneity in Go alpha mRNAs.
Animals↗
Mechanism of cholera toxin activation by a guanine nucleotide-dependent 19 kDa protein.
Cholera toxin causes the devastating diarrheal syndrome characteristic of cholera by catalyzing the ADP-ribosylation of Gs alpha, a GTP-binding regulatory protein, resulting in activation of adenylyl cyclase. ADP-ribosylation of Gs alpha is enhanced by 19 kDa guanine nucleotide-binding proteins known as ADP-ribosylation factors or ARFs. We investigated the effects of agents known to alter toxin-catalyzed activation of adenylyl cyclase on the stimulation of toxin- and toxin subunit-catalyzed ADP-ribosylation of Gs alpha and other substrates by an ADP-ribosylation factor purified from a soluble fraction of bovine brain (sARF II). In the presence of GTP, sARF II enhanced activity of both the toxin catalytic unit and a reduced and alkylated fragment ('A1'), as a result of an increase in substrate affinity with no significant effects on Vmax. Activation of toxin was independent of Gs alpha and was stimulated 4-fold by sodium dodecyl sulfate, but abolished by Triton X-100. sARF II therefore serves as a direct allosteric activator of the A1 protein and may thus amplify the pathological effects of cholera toxin.
ADP Ribose Transferases↗
Inhibition of histamine N-methyltransferase (HNMT) in vitro by neuromuscular relaxants.
There have been reports of hypotension and flushing following vecuronium administration. The etiology of these symptoms, which are similar to those of histamine release, is not clear. The steroidal neuromuscular relaxants (NMRs), unlike muscle relaxants structurally similar to curare, have been shown not to cause histamine release after the administration of typical clinical doses. Histamine levels in plasma reflect a balance between release and catabolism. In humans, histamine N-methyl-transferase (HNMT) is the enzyme primarily degrading for histamine. Therefore, we performed in vitro kinetic studies of purified HNMT to determine the effects of the steroidal and curare-like NMRs and also of gallamine on histamine catabolism. We demonstrated that all NMRs tested were inhibitors of HNMT in vitro. The inhibition was competitive with respect to the cosubstrate S-adenosyl-L-[3H-methyl] methionine, and noncompetitive with respect to histamine. The rank order of inhibition was vecuronium greater than pancuronium greater than gallamine greater than d-tubocurarine greater than metocurine greater than atracurium greater than pipecuronium, with Ki values ranging from 1.2 to 44.8 microM. Our data suggest that HNMT-based radioenzymatic assays for histamine should be susceptible to inhibition by concurrent use of NMRs, particularly vecuronium.
Androstane-3,17-diol↗
Mechanism of activation of cholera toxin by ADP-ribosylation factor (ARF): both low- and high-affinity interactions of ARF with guanine nucleotides promote toxin activation.
Activation of adenylyl cyclase by cholera toxin A subunit (CT-A) results from the ADP-ribosylation of the stimulatory guanine nucleotide binding protein (GS alpha). This process requires GTP and an endogenous guanine nucleotide binding protein known as ADP-ribosylation factor (ARF). One membrane (mARF) and two soluble forms (sARF I and sARF II) of ARF have been purified from bovine brain. Because the conditions reported to enhance the binding of guanine nucleotides by ARF differ from those observed to promote optimal activity, we sought to characterize the determinants influencing the functional interaction of guanine nucleotides with ARF. High-affinity GTP binding by sARF II (apparent KD of approximately 70 nM) required Mg2+, DMPC, and sodium cholate. sARF II, in DMPC/cholate, also enhanced CT-A ADP-ribosyltransferase activity (apparent EC50 for GTP of approximately 50 nM), although there was a delay before achievement of a maximal rate of sARF II stimulated toxin activity. The delay was abolished by incubation of sARF II with GTP at 30 degrees C before initiation of the assay. In contrast, a maximal rate of activation of toxin by sARF II, in 0.003% SDS, occurred without delay (apparent EC50 for GTP of approximately 5 microM). High-affinity GTP binding by sARF II was not detectable in SDS. Enhancement of CT-A ADP-ribosyltransferase activity by sARF II, therefore, can occur under conditions in which sARF II exhibits either a relatively low affinity or a relatively high affinity for GTP. The interaction of GTP with ARF under these conditions may reflect ways in which intracellular membrane and cytosolic environments modulate GTP-mediated activation of ARF.
ADP-Ribosylation Factors↗
Cardiac catheterization in the patient with history of allergy to local anesthetics.
Patients with a history of allergic reactions to local anesthetic drugs present a difficult problem during evaluation for cardiac catheterization procedures. In the worst cases the procedure may be deferred, or even performed without local anesthesia. In the vast majority of patients an acceptable agent for safe local anesthetic use can be found. Skin testing beginning with very dilute solutions of preservative-free local anesthetic agent may be administered easily. This report describes the practical aspects of skin testing and local anesthetic agent selection in patients with a history of allergic reaction to local anesthetic drugs.
Adult↗