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)

We have previously reported the selective amplification of several rat striatal cDNA sequences that encode guanine nucleotide-binding regulatory protein (G protein)-coupled receptors. One of these sequences (R226) exhibited high sequence identity (58%) with the two previously cloned adenosine receptors. A full-length cDNA clone for R226 has been isolated from a rat brain cDNA library. The cDNA clone encodes a protein of 320 amino acids that can be organized into seven transmembrane stretches. R226 has been expressed in COS-7 and CHO cells and membranes from the transfected cells were screened with adenosine receptor radioligands. R226 could bind the nonselective adenosine agonist tritiated N-ethyladenosine 5'-uronic acid ([3H]NECA) and A1-selective agonist radioiodinated N6-2-(4-amino-3-iodophenyl)-ethyladenosine ([125I]APNEA) but not A1-selective antagonists tritiated 1,3-dipropyl-8-cyclopentylxanthine ([3H]DPCPX) and 8-(4-[([[(2-aminoethyl)amino]carbonyl]methyl)oxy]-phenyl)-1, 3-dipropylxanthine ([3H]XAC) or the A2-selective agonist ligands tritiated 2-[4-(2-carboxyethyl)phenyl]ethyl-amino 5'-N-ethylcarboxamidoadenosine ([3H]CGS21680) and radioiodinated 2-[4-([2-[(4-aminophenyl)methylcarbonylamino] ethylaminocarbonyl]ethyl)phenyl]ethylamino 5'-N-ethylcarboxamidoadenosine. Extensive characterization with [125I]APNEA showed that R226 binds [125I]APNEA with high affinity (Kd = 15.5 +/- 2.4 nM) and the specific [125I]APNEA binding could be inhibited by adenosine ligands with a potency order of (R)-N6-phenyl-2-propyladenosine (R-PIA) = NECA greater than S-PIA greater than adenosine greater than ATP = ADP but not by antagonists XAC, isobutylmethylxanthine, and DPCPX. In R226 stably transfected CHO cells, adenosine agonists R-PIA, NECA, and CGS21680 inhibited by 40-50% the forskolin-stimulated cAMP accumulation through a pertussis toxin-sensitive G protein with an EC50 of 18 +/- 5.6 nM, 23 +/- 3.5 nM, and 144 +/- 34 nM, respectively. Based on these observations we conclude that R226 encodes an adenosine receptor with non-A1 and non-A2 specificity, and we thus name it the A3 adenosine receptor. mRNA analyses revealed that the highest expression of R226 was in the testis and low-level mRNAs were also found in the lung, kidneys, heart, and some parts of the central nervous system such as cortex, striatum, and olfactory bulb. The high-expression level of the A3 receptor in the testis suggests a possible role for adenosine in reproduction.
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PMID:Molecular cloning and characterization of an adenosine receptor: the A3 adenosine receptor. 132 36

Previous studies have shown that at least two subtypes of somatostatin (SRIF) receptors (SRIF1 and SRIF2) are expressed in mammalian cells. SRIF1 receptors have high affinity for MK 678, whereas SRIF2 receptors have no affinity for MK 678 but selectively bind peptides with structures similar to that of CGP 23996. Recently, two SRIF receptor genes have been cloned from human and mouse genomic libraries. In the present study, the pharmacological properties of these two cloned SRIF receptors, expressed in Chinese hamster ovary (CHO) cells, were investigated, to determine whether they have any similarity to the previously described SRIF1 and SRIF2 receptor subtypes. Both cloned receptors could be labeled with 125I-Tyr11-SRIF and exhibited high affinity for SRIF. The SSTR1 receptor could also bind CGP 23996-like compounds but not MK 678. In contrast, the SSTR2 receptor was insensitive to CGP 23996-like compounds but bound MK 678 with high affinity. These findings indicate that the peptide specificities of the cloned SSTR1 and SSTR2 receptors differ from each other. Pretreatment of CHO cells expressing the two cloned SRIF receptors with SRIF abolished high affinity agonist binding to the cloned SSTR2 receptor but not the cloned SSTR1 receptor. Agonist binding to SSTR1 receptors was not significantly affected by guanosine-5'-)-(3-thiotriphosphate) or pertussis toxin pretreatment, whereas agonist binding to SSTR2 receptors was inhibited by both treatments. These findings suggest that SSTR2 receptors can be regulated and they associate with pertussis toxin-sensitive guanine nucleotide-binding proteins, whereas SSTR1 receptors do not. SRIF is a potent inhibitor of adenylyl cyclase activity in mammalian cells. However, neither the cloned SSTR2 nor SSTR1 receptor mediated SRIF inhibition of adenylyl cyclase activity in stably transformed CHO cells or COS-1 cells transiently expressing the cloned receptors, suggesting that neither cloned receptor couples to adenylyl cyclase. The results of these studies indicate that the two cloned SRIF receptors have different pharmacological properties. The characteristics of the cloned SSTR2 receptor are similar to those of the previously described SRIF1 receptor, and the characteristics of the cloned SSTR1 receptor are similar to those of the previously described SRIF2 receptor.
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PMID:Pharmacological properties of two cloned somatostatin receptors. 135 50

To determine the effect of protein isoprenylation with farnesyl vs geranylgeranyl groups on membrane association in vivo, COS cells were transfected with cDNAs encoding the wild-type G-protein alpha i1 (WT) subunit, the soluble nonmyristoylated G-protein alpha i1 glycine to alanine mutant (GA), a double mutant in which the carboxy-terminal residues CGLF of GA were mutated to CVLS (GA-CVLS), and a double mutant in which the carboxy terminus of GA was mutated to CALL (GA-CALL). As opposed to the WT and GA proteins, the GA-CVLS and GA-CALL proteins were not pertussis toxin substrates nor were they recognized by antibodies that recognize the nonmutated alpha i1 carboxy terminus. Only the GA-CVLS and GA-CALL proteins incorporated [3H]mevalonate in the form of a farnesyl and a geranylgeranyl moiety, respectively. Subcellular localization, as assessed by immunoblotting and immunoprecipitation, revealed that the WT protein localizes almost exclusively to the membrane fraction, whereas the GA, GA-CVLS, and GA-CALL proteins localize predominantly to the soluble fraction. The soluble GA-CVLS and GA-CALL proteins were not carboxyl methylated, but the small amount localized to the membrane was partially carboxyl methylated. These results indicate that neither farnesylation nor geranylgeranylation is sufficient alone to lead to membrane association.
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PMID:Differential isoprenylation of carboxy-terminal mutants of an inhibitory G-protein alpha-subunit: neither farnesylation nor geranylgeranylation is sufficient for membrane attachment. 151 Sep 88

Human kidney 293 TSA cells were transfected by a calcium phosphate method with human formylpeptide and C5a receptor cDNAs with high efficiency. Formylpeptide receptor positive transfectants expressed a total of 968,000 +/- 34,000 receptors per cell with two affinity states (Kds of ca. 0.43 nM and 39 nM), which in the presence of 100 microM GTP gamma S decreased by ca. 4-fold the number of high-affinity sites. The ligand binding pharmacology of cloned and expressed formylpeptide receptors were indistinguishable from endogenous receptors on human neutrophils. Expressed formylpeptide and C5a receptors were functionally active in mobilizing intracellular calcium via a pertussis toxin sensitive mechanism with an ED50 for formylpeptide of ca. 0.5-1.0 nM. This expression system, in which receptor expression can be monitored by flow cytometric methods and in which intracellular calcium responses are measurable, unlike in the more popular COS-7 cell expression system, will provide a useful basis for the analysis of chemoattractant receptor structure-function relationships.
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PMID:Functional high efficiency expression of cloned leukocyte chemoattractant receptor cDNAs. 154 8

We recently reported the cloning of a novel alpha 1-adrenergic receptor (AR), the alpha 1CAR. By transient and stable expression of the alpha 1CAR and the previously cloned alpha 1BAR in COS-7 and HeLa cells, respectively, we have now compared their ability to interact with major signal-transduction pathways (including polyphosphoinositide hydrolysis, intracellular calcium, and cAMP metabolism), as well as their mammalian tissue localization. Both alpha 1C- and alpha 1BARs primarily couple to phospholipase C via a pertussis toxin-insensitive GTP-binding protein, leading to the release of calcium from intracellular stores. Even though alpha 1C- and alpha 1BARs activate polyphosphoinositide hydrolysis by similar biochemical mechanisms, the alpha 1CAR couples to phospholipase C more efficiently than does the alpha 1BAR; activation of the alpha 1CAR results in a 2-3-fold greater increase in inositol phosphates, compared with the alpha 1BAR. Both alpha 1AR subtypes can also increase intracellular cAMP, by a mechanism that does not involve direct activation of adenylyl cyclase. In agreement with ligand binding data, the agonist methoxamine and the antagonist WB4101 are 10-fold more potent in activating or inhibiting, respectively, the ability of the alpha 1CAR to stimulate phospholipase C, compared with the alpha 1BAR. In addition, methoxamine is almost a full agonist at the alpha 1CAR, whereas it can only weakly activate the alpha 1BAR. Tissue localization, using Northern blot analysis of total and poly(A)+-selected RNA from rabbit tissues, revealed striking mammalian species heterogeneity. As previously described, the alpha 1BAR is present in several rat tissues, including heart, liver, brain, kidney, lung, and spleen, whereas the alpha 1CAR is not present in any rat tissue studied. The alpha 1BAR is also present in rabbit aorta, heart, spleen, and kidney (and absent in rabbit liver), whereas the alpha 1CAR is present in rabbit liver. Our results indicate that the cloning and expression of different alpha 1AR subtypes represents a valuable tool to elucidate functional correlates of alpha 1AR heterogeneity.
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PMID:The alpha 1C-adrenergic receptor: characterization of signal transduction pathways and mammalian tissue heterogeneity. 165

Signal-transduction pathways mediated by guanine nucleotide-binding regulatory proteins (G proteins) determine many of the responses of hematopoietic cells. A recently identified gene encoding a G protein alpha subunit, G alpha 16, is specifically expressed in human cells of the hematopoietic lineage. The G alpha 16 cDNA encodes a protein with predicted Mr of 43,500, which resembles the G q class of alpha subunits and does not include a pertussis toxin ADP-ribosylation site. In comparison with other G protein alpha subunits, the G alpha 16 predicted protein has distinctive amino acid sequences in the amino terminus, the region A guanine nucleotide-binding domain, and in the carboxyl-terminal third of the protein. Cell lines of myelomonocytic and T-cell phenotype express the G alpha 16 gene, but no expression is detectable in two B-cell lines or in nonhematopoietic cell lines. G alpha 16 gene expression is down-regulated in HL-60 cells induced to differentiate to neutrophils with dimethyl sulfoxide. Antisera generated from synthetic peptides that correspond to two regions of G alpha 16 specifically react with a protein of 42- to 43-kDa in bacterial strains that overexpress G alpha 16 and in HL-60 membranes. This protein is decreased in membranes from dimethyl sulfoxide-differentiated HL-60 cells and is not detectable in COS cell membranes. The restricted expression of this gene suggests that G alpha 16 regulates cell-type-specific signal-transduction pathways, which are not inhibited by pertussis toxin.
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PMID:G alpha 16, a G protein alpha subunit specifically expressed in hematopoietic cells. 190 13

We transfected COS cells with cDNAs for the alpha subunits of stimulatory and inhibitory GTP-binding proteins, alpha s and alpha i1, respectively, and immunoprecipitated the metabolically labeled products with specific peptide antibodies. Cells were separated into particulate and soluble fractions before immunoprecipitation; [35S]methionine-labeled alpha s and alpha i were both found primarily in the particulate fraction. [3H]Myristate was incorporated into endogenous and transfected alpha i but could not be detected in alpha s even when it was overexpressed. We converted the second residue, glycine, of alpha i1 into alanine by site-directed mutagenesis. Upon transfection of the mutant alpha i1 into COS cells, the [35S]methionine-labeled product was localized primarily to the soluble fraction, and, also unlike normal alpha i1, the mutant failed to incorporate [3H]myristate. The unmyristoylated mutant alpha i1 could still interact with the beta-gamma complex, since purified beta gamma subunits promoted pertussis toxin-catalyzed ADP-ribosylation of both the normal and mutant alpha i1 subunits. These results indicate that myristoylation is critical for membrane attachment of alpha i but not alpha s subunits.
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PMID:Myristoylation of an inhibitory GTP-binding protein alpha subunit is essential for its membrane attachment. 210 88

We transfected COS cells with expression vectors for the wild-type G protein alpha i1 subunit (pWT) and for mutated alpha i1 subunits, including the nonmyristylated glycine 2 to alanine mutant (pGA) and mutants in which the carboxyl termini of pWT and pGA were changed from CGLF to CVLS (pCVLS and pGA-CVLS, respectively). Immunoblot analysis of transfected COS cells with an antibody to residues 159-168 of the alpha i1 protein indicated that all four proteins were expressed. Unlike the WT and GA proteins, both CVLS mutant proteins failed to react with an antibody specific for the carboxyl terminus and failed to undergo pertussis toxin-catalyzed ADP-ribosylation. Analysis of COS cell lysates after [3H]mevalonic acid labeling indicated that specific incorporation of radioactivity occurred only in the alpha i1 subunits with the CVLS mutation. Immuno-precipitation of COS cell fractions after labeling with [35S]methionine indicated that both WT and CVLS mutant proteins were localized predominantly in the particulate fraction, whereas GA and GA-CVLS mutant proteins were found primarily in the soluble fraction. These results directly demonstrate that the carboxyl-terminal sequence, CGLF, is incapable of leading to isoprenylation but that alteration of two residues (glycine to valine, phenylalanine to serine) is sufficient to promote isoprenylation.
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PMID:Isoprenylation of an inhibitory G protein alpha subunit occurs only upon mutagenesis of the carboxyl terminus. 212 86

The signal transduction pathways of the cloned human 5-HT1A receptor have been examined in two mammalian cell lines transiently (COS-7) or permanently (HeLa) expressing this receptor gene. In both systems, 5-hydroxytryptamine (5-HT, serotonin) mediated a marked inhibition of beta 2-adrenergic agonist-stimulated (80% inhibition in COS-7 cells) or forskolin-stimulated cAMP formation (up to 90% inhibition in HeLa cells). This serotonin effect (EC50 = 20 nM) could be competitively antagonized by metitepine and spiperone (Ki = 81 and 31 nM, respectively) and could also be blocked by pretreatment of cells with pertussis toxin. In both cell types, 5-HT failed to stimulate adenylyl cyclase through the expressed receptors. In HeLa cells, 5-HT also stimulated phospholipase C (approximately 40-75% stimulation of formation of inositol phosphates). Again, this effect was inhibited by metitepine. However, the EC50 of 5-HT was considerably higher (approximately 3.2 microM) than that found for inhibition of adenylyl cyclase. Both pathways were demonstrated to be similarly affected by pertussis toxin. These findings indicate that like the M2 and M3 muscarinic cholinergic receptors, the 5-HT1A receptor can couple to multiple transduction pathways with varying efficiencies via pertussis toxin-sensitive G-proteins. The lack of stimulation of cAMP formation by this 5-HT1A receptor may suggest the existence of another pharmacologically closely related receptor.
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PMID:Effector coupling mechanisms of the cloned 5-HT1A receptor. 254 39

Luteinizing hormone is the major regulator of Leydig cell differentiation and steroidogenic function. A number of hormones produced by the Leydig cell (e.g. estrogen, angiotensin, CRF, vasopressin) and the tubular compartment (inhibin, TGF beta), can influence both acute and long-term actions of LH. Conversely, hormones produced in the Leydig cells modulate tubular function (e.g. androgen, beta-endorphin, oxytocin). The LH stimulatory event can be negatively influenced by the action of angiotensin II through the guanyl nucleotide inhibitory unit of adenylate cyclase. We have recently discovered an action of corticotrophin releasing hormone through specific high-affinity low-capacity receptors in the Leydig cells which involves a pertussis toxin insensitive guanyl nucleotide regulatory unit with interaction between signalling pathways and resulting inhibition of LH induced cAMP generation and consequently of steroidogenesis. In contrast to other tissues the CRF receptor in the Leydig cells did not couple to Gs. CRF action is exerted through direct or indirect action of protein kinase C, at the level of the catalytic subunit of adenylate cyclase. Physiological increases in endogenous LH cause positive regulation of membrane receptors and steroidogenesis, while major elevations in circulating gonadotropin can induce down-regulation of LH receptors and desensitization of steroid responses in the adult cell. Gonadotropin-induced desensitization in adult rat tests include an estrogen mediated steroidogenic lesion of the microsomal enzymes 17 alpha-hydroxylase/17,20-desmolase. For further understanding of the regulation of this key enzyme of the androgen pathway the rat P450(17) alpha cDNA was cloned and sequenced. This cDNA expressed in COS-1 cells 17 alpha-hydroxylase/17,20-desmolase activities. From the deduced amino acid sequence, two transmembrane regions were identified, a signal peptide for insertion in the ER, and a 2nd transmembrane region separated from the first by 122 amino acids. The carboxy terminal non-transmembrane region possesses 4 hydrophobic clefts, of which cleft II would contain the putative steroid binding site for both hydroxylase and lyase activities. The rat cDNA was employed to evaluate the hormonal regulation of mRNA levels in adult and fetal Leydig cells. Low dose hCG treatment caused an early increase in mRNA levels followed by a return to control values at later times, while with higher desensitizing doses the initial increase in mRNA was followed by a marked reduction in mRNA at 24 h and a small recovery at 48 h. Fetal rat Leydig cells treated with E2 showed a 70% decrease in P450 mRNA levels, and testosterone production closely followed the changes in mRNA.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:LH action in the Leydig cell: modulation by angiotensin II and corticotropin releasing hormone, and regulation of P450(17) alpha mRNA. 269 45


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