Receptors & channels最新文献_第8页

Scanning mutagenesis studies of the M1 muscarinic acetylcholine receptor. M1毒蕈碱乙酰胆碱受体的扫描诱变研究。

Receptors & channels Pub Date : 2003-01-01

E C Hulme, Z L Lu, M S Bee

{"title":"Scanning mutagenesis studies of the M1 muscarinic acetylcholine receptor.","authors":"E C Hulme, Z L Lu, M S Bee","doi":"","DOIUrl":"","url":null,"abstract":"Following the solution of the structure of bovine rhodopsin by X-ray crystallography, it has been possible to build an improved homology model of the M(1) muscarinic acetylcholine receptor. This has been used to interpret the outcome of an extensive series of scanning and point mutagenesis studies on the transmembrane domain of the receptor. Potential intramolecular interactions enhancing the stability of the protein fold have been identified. The residues contributing to the binding site for the antagonist, N-methylscopolamine, and the agonist, acetylcholine have been mapped. The positively charged headgroups of these ligands appear to bind in a charge-stabilized aromatic cage formed by amino acid side chains in transmembrane (TM) helices 3, 6, and 7, while residues in TM 4 may participate in a peripheral docking site. Closure of the cage around the headgroup of acetylcholine may help to transduce binding energy into receptor activation, possibly disrupting a set of Van der Waals interactions between a set of residues underlying the binding site which help to constrain the receptor to the inactive state, in the absence of agonist. This may trigger the reorganization of a hydrogen bonding network between highly conserved residues in the core of the receptor, whose integrity is crucial for activation.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22509788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Characterization of adenosine A1 receptors in human proximal tubule epithelial (HK-2) cells. 人近端小管上皮细胞(HK-2)中腺苷A1受体的表征。

Receptors & channels Pub Date : 2003-01-01

Yuting Tang, Lubing Zhou

{"title":"Characterization of adenosine A1 receptors in human proximal tubule epithelial (HK-2) cells.","authors":"Yuting Tang, Lubing Zhou","doi":"","DOIUrl":"","url":null,"abstract":"Background: Adenosine A1 receptors (A1ARs) modulate various aspects of renal functions, such as hormone release, hemodynamics and tubular absorption. Here we set up to demonstrate the expression of A1ARs in an immortalized cell line (HK-2) derived from normal adult human proximal tubule. We also examined the mechanism whereby A1ARs signal in HK-2 cells and their potential role in renal physiology such as sodium-dependent phosphate transport.Methods: Ligand binding assay of A1ARs was performed using plasma membranes of HK-2 cells and a selective high-affinity A1AR radioligand [3H]DPCPX. HK-2 cells in 96-well plates were treated with various agents (forskolin, adenosine receptor agonists, and antagonists) to activate or inhibit adenylate cyclase. Intracellular cyclic AMP accumulation was measured using cAMP flashplates. mRNA levels of adenosine receptors in HK-2 cells was determined by real-time PCR technique. Sodium-dependent phosphate transport across cell membrane was measured after 15-minute incubation of phosphorus-33 in transport buffer with HK-2 cells at room temperature.Results: In HK-2 cells, A1ARs were expressed at a density of 211 +/- 74 fmol/mg membrane proteins. [3H]DPCPX bound to A1ARs on HK-2 cell membranes with Kd of 8.3 +/- 2.2 nM. Activation of A1ARs inhibited isoproterenol-stimulated adenylate cyclase activity through pertussis toxin-sensitive Gi protein in HK-2 cells. Coexpression of adenosine A2a receptors at a seemingly lower level than A1ARs was revealed by synergistically activating adenylate cyclase with forskolin. Real-time RT-PCR further demonstrated the expression of both A1AR and A2aAR in HK-2 cells. Sodium-dependent phosphate transport was augmented by activation of A1ARs in HK-2 cells.Conclusion: A1ARs are expressed in human proximal tubule epithelial (HK-2) cells and modulate sodium-dependent phosphate transport.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22529263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Putative dynamics of vasopressin in its V1a receptor binding site. 抗利尿激素在其V1a受体结合位点的推测动力学。

Receptors & channels Pub Date : 2003-01-01

Astrid Kaltenböck, Marcel Hibert, Thierry Langer

{"title":"Putative dynamics of vasopressin in its V1a receptor binding site.","authors":"Astrid Kaltenböck, Marcel Hibert, Thierry Langer","doi":"","DOIUrl":"","url":null,"abstract":"The molecular architecture of the GPCRs, including the dynamic set of interactions between the receptor and the ligand, is one of the key structural questions of biophysical approaches. In the present study, molecular dynamics (MD) simulations were performed on the well-validated molecular model of the vasopressin V1a receptor applying different parameters (i.e., force fields, time variation, use of constraints) in order to sample the conformational space of the endogenous ligand arginine vasopressin (AVP), to explore different putative binding modes, and to analyze the simulation results with respect to experimental data. Noteworthy, it is to mention that for the first time a model of the vasopressin receptor remained stable in a 500 ps MD simulation run under vacuo boundary conditions using the Kollman all-atom FF even though no constraints were imposed. Conclusively, we determined an optimized experimental procedure for studying the dynamics and structure-functionship of this highly important family of GPCRs: the use of MD simulations with the Kollman all-atom force-field parameters on a constrained receptor. Our simplified model may be used as a basis for structure based design of new GPCR ligands and for in silico screening of virtual combinatorial chemistry libraries.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22529266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

M1-M5 muscarinic receptor knockout mice as novel tools to study the physiological roles of the muscarinic cholinergic system. M1-M5毒蕈碱受体敲除小鼠作为研究毒蕈碱胆碱能系统生理作用的新工具。

Receptors & channels Pub Date : 2003-01-01 DOI: 10.1080/10606820308262

J. Wess, A. Duttaroy, Weilie Zhang, J. Gomeza, Yinghong Cui, Tsuyoshi Miyakawa, F. Bymaster, L. Mckinzie, C. Felder, Kathryn G. Lamping, F. Faraci, Chu-Xia Deng, Masahisa Yamada

{"title":"M1-M5 muscarinic receptor knockout mice as novel tools to study the physiological roles of the muscarinic cholinergic system.","authors":"J. Wess, A. Duttaroy, Weilie Zhang, J. Gomeza, Yinghong Cui, Tsuyoshi Miyakawa, F. Bymaster, L. Mckinzie, C. Felder, Kathryn G. Lamping, F. Faraci, Chu-Xia Deng, Masahisa Yamada","doi":"10.1080/10606820308262","DOIUrl":"https://doi.org/10.1080/10606820308262","url":null,"abstract":"A large body of evidence indicates that muscarinic acetylcholine receptors (mAChRs) play critical roles in regulating the activity of many important functions of the central and peripheral nervous systems. However, identification of the physiological and pathophysiological roles of the individual mAChR subtypes (M(1)-M(5)) has proven a difficult task, primarily due to the lack of ligands endowed with a high degree of receptor subtype selectivity and the fact that most tissues and organs express multiple mAChRs. To circumvent these difficulties, we used gene targeting technology to generate mutant mouse lines containing inactivating mutations of the M(1)-M(5) mAChR genes. The different mAChR mutant mice and the corresponding wild-type control animals were subjected to a battery of physiological, pharmacological, behavioral, biochemical, and neurochemical tests. The M(1)-M(5) mAChR mutant mice were viable and reproduced normally. However, each mutant line displayed specific functional deficits, suggesting that each mAChR subtype mediates distinct physiological functions. These results should offer new perspectives for the rational development of novel muscarinic drugs.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82997266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 107

Guest Editor's Introduction: G Protein-Mediated Signaling: Some Complex Issues 客座编辑介绍:G蛋白介导的信号传导:一些复杂的问题

Receptors & channels Pub Date : 2003-01-01 DOI: 10.3109/10606820308241

P. Chidiac

引用次数: 2

Characterization of adenosine A1 receptors in human proximal tubule epithelial (HK-2) cells. 人近端小管上皮细胞(HK-2)中腺苷A1受体的表征。

Receptors & channels Pub Date : 2003-01-01 DOI: 10.3109/10606820308250

Yuting Tang, Lubing Zhou

{"title":"Characterization of adenosine A1 receptors in human proximal tubule epithelial (HK-2) cells.","authors":"Yuting Tang, Lubing Zhou","doi":"10.3109/10606820308250","DOIUrl":"https://doi.org/10.3109/10606820308250","url":null,"abstract":"BACKGROUND Adenosine A1 receptors (A1ARs) modulate various aspects of renal functions, such as hormone release, hemodynamics and tubular absorption. Here we set up to demonstrate the expression of A1ARs in an immortalized cell line (HK-2) derived from normal adult human proximal tubule. We also examined the mechanism whereby A1ARs signal in HK-2 cells and their potential role in renal physiology such as sodium-dependent phosphate transport. METHODS Ligand binding assay of A1ARs was performed using plasma membranes of HK-2 cells and a selective high-affinity A1AR radioligand [3H]DPCPX. HK-2 cells in 96-well plates were treated with various agents (forskolin, adenosine receptor agonists, and antagonists) to activate or inhibit adenylate cyclase. Intracellular cyclic AMP accumulation was measured using cAMP flashplates. mRNA levels of adenosine receptors in HK-2 cells was determined by real-time PCR technique. Sodium-dependent phosphate transport across cell membrane was measured after 15-minute incubation of phosphorus-33 in transport buffer with HK-2 cells at room temperature. RESULTS In HK-2 cells, A1ARs were expressed at a density of 211 +/- 74 fmol/mg membrane proteins. [3H]DPCPX bound to A1ARs on HK-2 cell membranes with Kd of 8.3 +/- 2.2 nM. Activation of A1ARs inhibited isoproterenol-stimulated adenylate cyclase activity through pertussis toxin-sensitive Gi protein in HK-2 cells. Coexpression of adenosine A2a receptors at a seemingly lower level than A1ARs was revealed by synergistically activating adenylate cyclase with forskolin. Real-time RT-PCR further demonstrated the expression of both A1AR and A2aAR in HK-2 cells. Sodium-dependent phosphate transport was augmented by activation of A1ARs in HK-2 cells. CONCLUSION A1ARs are expressed in human proximal tubule epithelial (HK-2) cells and modulate sodium-dependent phosphate transport.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75032764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 21

Genetic approaches to visual transduction in Drosophila melanogaster. 黑腹果蝇视觉转导的遗传研究。

Receptors & channels Pub Date : 2003-01-01

William L Pak, Hung-Tat Leung

{"title":"Genetic approaches to visual transduction in Drosophila melanogaster.","authors":"William L Pak, Hung-Tat Leung","doi":"","DOIUrl":"","url":null,"abstract":"Because almost everything we know about Drosophila phototransduction has come from studies based on genetic approaches, this review begins with a discussion of genetic approaches. We then present a brief overview of Drosophila phototransduction (section on Drosophila phototransduction: an overview) followed by a more detailed treatment of individual components of the transduction machinery (section on Components of the phototransduction machinery). Discussion of transduction mechanisms is presented under three headings: Mechanism(s) of channel excitation, Organization of the transduction proteins, and Regulatory mechanisms in phototransduction. Perhaps the most important unanswered question in this field is the mechanism(s) of activation and regulation of transduction channels. This question is explored in the section entitled Mechanism(s) of channel excitation. Identification of at least two of the proteins discussed was totally unexpected: the rhodopsin chaperone protein, ninaA, and the signal complex scaffold protein, INAD. They are discussed in the sections titled Requirement for a chaperone protein for Rh1 opsin, and: Formation of signaling complexes, respectively. One of the important developments in this field has been the discovery of mammalian homologs of many of the proteins identified in Drosophila. A brief discussion of the most extensively studied of these, the mammalian homologs of light-activated channel protein, trp, is presented in the section on Mammalian Homologs of trp. We conclude the review with Perspective, a brief look at the current status and the future outlook of the field.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22409913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

CYTOCENTERING: a novel technique enabling automated cell-by-cell patch clamping with the CYTOPATCH chip. 细胞定心:一种新颖的技术，可以使用CYTOPATCH芯片实现细胞对细胞的自动贴片夹紧。

Receptors & channels Pub Date : 2003-01-01

Alfred Stett, Claus Burkhardt, Uli Weber, Peter van Stiphout, Thomas Knott

{"title":"CYTOCENTERING: a novel technique enabling automated cell-by-cell patch clamping with the CYTOPATCH chip.","authors":"Alfred Stett, Claus Burkhardt, Uli Weber, Peter van Stiphout, Thomas Knott","doi":"","DOIUrl":"","url":null,"abstract":"Automats for patch clamping suspended cells in whole-cell configuration must (1) bring isolated cells in contact with patch contacts, (2) form gigaseals, and (3) establish stable intracellular access that allows for high quality recording of ionic currents. Single openings in planar substrates seem to be intriguing simple solutions for these problems, but due to the low rate of formation of whole-cell configurations we discarded this approach. Single openings are not suited for both attracting cells to the opening by suction and forming gigaseals with subsequent membrane rupture. To settle the three tasks with a mechanical microstructure we developed the socalled CYTOCENTERING technique to apply to suspended cells the same operation sequence as in conventional patch clamping. With this method we immobilized selected cells from a flowing suspension on the tip of a patch pipette by suction with a success rate of 97% and formed gigaseals with a success rate of 68%. Subsequent whole-cell recordings and intracellular staining with Lucifer yellow proved the stable access to the cytoplasm. Currently, a chip with an embedded suction opening in glass surrounding the microstructured contact pipette is under development. The processing of this CYTOPATCH chip is compatible to large-volume production. The CYTOPATCH automat will allow for fully automated, parallel, and asynchronous whole-cell recordings.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22453900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Combined effects of Cordyceps sinensis and methotrexate on hematogenic lung metastasis in mice. 冬虫夏草联合甲氨蝶呤对小鼠血源性肺转移的影响。

Receptors & channels Pub Date : 2003-01-01 DOI: 10.3109/713745176

Kazuki Nakamura, Keiko Konoha, Yu Yamaguchi, Satomi Kagota, Kazumasa Shinozuka, Masaru Kunitomo

{"title":"Combined effects of Cordyceps sinensis and methotrexate on hematogenic lung metastasis in mice.","authors":"Kazuki Nakamura, Keiko Konoha, Yu Yamaguchi, Satomi Kagota, Kazumasa Shinozuka, Masaru Kunitomo","doi":"10.3109/713745176","DOIUrl":"https://doi.org/10.3109/713745176","url":null,"abstract":"We investigated antitumor effects of water extracts of Cordyceps sinensis (WECS). WECS (100 microg/ml) induced apoptosis of B16 melanoma cells after 48 h exposure in vitro as determined by both the TUNEL (TdT-mediated dUTP-biotin nick end labeling) method and the detection of a DNA ladder. In vivo, combined treatment with WECS and methotrexate (MTX) in mice intravenously inoculated with B16 melanoma cells was conducted. Although MTX caused a significant and severe decrease in body weight compared with that in control mice starting 16 days after the start of administration, the mice given both MTX and WECS did not show a significant decrease in body weight. The mean survival time (days) of the control mice, MTX-treated mice (15 mg/kg/day, s.c.), and WECS-treated mice (200 mg/kg/day, p.o.) was 25.0 +/- 0.3, 25.6 +/- 1.3, and 25.7 +/- 1.0 (mean +/- S.E.M. of 6-7 mice), respectively. On the other hand, mean survival time (days) of mice given the combination of MTX and WECS was 28.2 +/- 0.7, significantly longer than the control value. WECS might be beneficial in the prevention of tumor metastasis as an adjuvant agent in cancer chemotherapy.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.3109/713745176","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"24014304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 49

Development of a high-throughput viral-free assay for the measurement of CCR5-mediated HIV/cell fusion. 高通量无病毒检测ccr5介导的HIV/细胞融合的发展。

Receptors & channels Pub Date : 2003-01-01

Stephen Jenkinson, David McCoy, Sandy Kerner, Rob Ferris, Wendell Lawrence, Tony Fox, Chari Smith

{"title":"Development of a high-throughput viral-free assay for the measurement of CCR5-mediated HIV/cell fusion.","authors":"Stephen Jenkinson, David McCoy, Sandy Kerner, Rob Ferris, Wendell Lawrence, Tony Fox, Chari Smith","doi":"","DOIUrl":"","url":null,"abstract":"M-tropic HIV strains gain access to their host cell via interaction of the viral envelope protein gp120 with the CCR5 coreceptor and CD4 located on the host cell. Inhibition of this event has been shown to reduce viral fusion and entry into cells in vitro. In the present study we describe the development of a novel cell/cell fusion assay that both mimics the viral/cell fusion process and allows quantification of this event. The assay has been characterized both biochemically, using selective antibodies, and pharmacologically, using selective CCR5 antagonists, and has been shown to be selective for examining the interaction of viral gp120 with hCCR5/hCD4. In addition, compound pIC50 data obtained from this cell/cell fusion assay correlates well (r2 = 0.7274) with data obtained from an HIV-1 replication assay. Furthermore, this assay has the added ability to simultaneously determine compound toxicity, thus allowing rapid determination of active, non-toxic compounds. In conclusion, the cell/cell fusion assay developed has been demonstrated to be a suitable surrogate assay that can be used to assess the effects of compounds on gp120/CCR5/CD4 mediated viral fusion into host cells.","PeriodicalId":20928,"journal":{"name":"Receptors & channels","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2003-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"22529268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0