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Cullum SA, Platt S, Dale N, Isaac OC, Wragg ES, Soave M, Veprintsev DB, Woolard J, Kilpatrick LE, Hill SJ. Mechano-sensitivity of β2-adrenoceptors enhances constitutive activation of cAMP generation that is inhibited by inverse agonists. Commun Biol 2024; 7:417. [PMID: 38580813 PMCID: PMC10997663 DOI: 10.1038/s42003-024-06128-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 03/29/2024] [Indexed: 04/07/2024] Open
Abstract
The concept of agonist-independent signalling that can be attenuated by inverse agonists is a fundamental element of the cubic ternary complex model of G protein-coupled receptor (GPCR) activation. This model shows how a GPCR can exist in two conformational states in the absence of ligands; an inactive R state and an active R* state that differ in their affinities for agonists, inverse agonists, and G-protein alpha subunits. The proportion of R* receptors that exist in the absence of agonists determines the level of constitutive receptor activity. In this study we demonstrate that mechanical stimulation can induce β2-adrenoceptor agonist-independent Gs-mediated cAMP signalling that is sensitive to inhibition by inverse agonists such as ICI-118551 and propranolol. The size of the mechano-sensitive response is dependent on the cell surface receptor expression level in HEK293G cells, is still observed in a ligand-binding deficient D113A mutant β2-adrenoceptor and can be attenuated by site-directed mutagenesis of the extracellular N-glycosylation sites on the N-terminus and second extracellular loop of the β2-adrenoceptor. Similar mechano-sensitive agonist-independent responses are observed in HEK293G cells overexpressing the A2A-adenosine receptor. These data provide new insights into how agonist-independent constitutive receptor activity can be enhanced by mechanical stimulation and regulated by inverse agonists.
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Affiliation(s)
- Sean A Cullum
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Simon Platt
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Natasha Dale
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Oliver C Isaac
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Edward S Wragg
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Mark Soave
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Dmitry B Veprintsev
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Jeanette Woolard
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
| | - Laura E Kilpatrick
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK
- Division of Bimolecular Science and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK.
- Centre of Membrane Proteins and Receptors, University of Nottingham, Nottingham, NG7 2UH, UK.
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2
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Li X, Zhou M, Huang W, Yang H. N-glycosylation of the β2
adrenergic receptor regulates receptor function by modulating dimerization. FEBS J 2017; 284:2004-2018. [DOI: 10.1111/febs.14098] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 04/10/2017] [Accepted: 04/28/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Xiaona Li
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai China
- The University of Chinese Academy of Sciences; Beijing China
| | - Mang Zhou
- CAS Key Laboratory of Receptor Research; CAS Center for Excellence in Molecular Cell Science; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Pudong, Shanghai China
| | - Wei Huang
- CAS Key Laboratory of Receptor Research; CAS Center for Excellence in Molecular Cell Science; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Pudong, Shanghai China
| | - Huaiyu Yang
- Drug Discovery and Design Center; State Key Laboratory of Drug Research; Shanghai Institute of Materia Medica; Chinese Academy of Sciences; Shanghai China
- Shanghai Universities E-Institute for Chemical Biology; China
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3
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4
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Szczepankiewicz A, Breborowicz A, Sobkowiak P, Kramer L, Popiel A. Role of ADRB2 gene polymorphism in asthma and response to beta(2)-agonists in Polish children. J Appl Genet 2009; 50:275-81. [PMID: 19638684 DOI: 10.1007/bf03195683] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aims of this study were: (1) to find associations of asthma with single-nucleotide polymorphisms (SNPs) within the ADRB2 gene: Arg16Gly, Gln27Glu, -1023 G/A, -367 T/C, -47 C/T ; (2) to define linkage disequilibrium in the gene region, basing on the analyzed SNPs; and (3) to analyze the importance of ADRB2 polymorphism for response to bronchodilator drugs in children diagnosed with bronchial asthma. We compared 113 asthmatic children and 123 healthy subjects from the Polish population. Genotyping was performed by PCR-RFLP. We found an association of the A allele of -1023A/G ADRB2 polymorphism with asthma (P = 0.024). No significant associations with other SNPs were detected. Moderate linkage was found between Gln27Glu and -47C/T polymorphisms in linkage disequilibrium analysis (D' = 0.85, r(2) = 0.429, LOD = 31.97). No significant differences were found in haplotype frequencies in comparison to the control group, implicating that they are not associated with susceptibility to asthma in the analyzed population. There was no significant correlation between the analyzed SNPs of the ADRB2 gene and the response to beta(2)-agonists. This is the first report providing suggestive evidence for association of -1023A/G ADRB2 polymorphism with an increased risk of asthma. The analyzed SNPs may not play a major role in response to beta(2)-agonists in asthmatic children.
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Affiliation(s)
- A Szczepankiewicz
- Department of Pediatric Pulmonology, Allergy and Clinical Immunology, Poznan University of Medical Sciences, Poland.
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5
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Oostendorp J, Postma DS, Volders H, Jongepier H, Kauffman HF, Boezen HM, Meyers DA, Bleecker ER, Nelemans SA, Zaagsma J, Meurs H. Differential desensitization of homozygous haplotypes of the beta2-adrenergic receptor in lymphocytes. Am J Respir Crit Care Med 2005; 172:322-8. [PMID: 15879418 PMCID: PMC2718471 DOI: 10.1164/rccm.200409-1162oc] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Accepted: 04/25/2005] [Indexed: 11/16/2022] Open
Abstract
Single-nucleotide polymorphisms of the beta(2)-adrenergic receptor gene and its 5' promoter have been associated with differences in receptor function and desensitization. Linkage disequilibrium may account for inconsistencies in reported effects of isolated polymorphisms. Therefore, we have investigated the three most common homozygous haplotypes of the beta(2)-adrenergic receptor (position 19 [Cys/Arg] of the 5' leader cistron and positions 16 [Arg/Gly] and 27 [Gln/Glu] of the receptor) for putative differences in agonist-induced desensitization. Lymphocytes of well defined nonasthmatic, nonallergic subjects homozygous for the haplotype CysGlyGln, ArgGlyGlu, or CysArgGln were isolated. Desensitization of (-)-isoproterenol-induced cyclic adenosine monophosphate (cAMP) accumulation and beta(2)-adrenergic receptor sequestration and downregulation were measured in relation to beta(2)-adrenergic receptor-mediated inhibition of IFN-gamma and interleukin-5 production. We observed that lymphocytes of individuals bearing the CysGlyGln haplotype were more susceptible to desensitization of the beta-agonist-induced cAMP response than those of individuals with the ArgGlyGlu or CysArgGln haplotype. The haplotype-dependent desensitization of beta-agonist-induced cAMP response was not associated with haplotype-dependent beta(2)-adrenergic receptor sequestration or downregulation. In addition, our data suggest reduced inhibition, in lymphocytes of subjects with the CysGlyGln haplotype, of interleukin-5 production induced by treatment with antibodies to the T-cell receptor-CD3 complex and to costimulatory molecule CD28 (alphaCD3/alphaCD28). This is the first study demonstrating haplotype-related differences in agonist-induced beta(2)-adrenergic receptor desensitization in primary human cells. This haplotype-related desensitization of the beta(2)-adrenergic receptor in lymphocytes might have consequences regarding the regulation of helper T-cell type 2 inflammatory responses.
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Affiliation(s)
- Jaap Oostendorp
- Department of Molecular Pharmacology, University of Groningen, The Netherlands
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6
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Abstract
Nine membrane-bound members of the mammalian adenylate cyclase family have been identified. The least characterized and most divergent in sequence of the nine adenylate cyclase isoforms is AC9. Stimulation by Galpha(s) and inhibition by Ca2+/calcineurin are two modes of regulation that have been reported for AC9. We explored the possibility of additional modes of regulation of human AC9. We now report that quinpirole activation of the inhibitory G protein-coupled D2L dopamine receptor inhibits Galpha(s) stimulation of AC9 by approximately 50%. The effects of quinpirole were reversed by the D2 antagonist spiperone and by pertussis toxin pretreatment. We also report the first evidence for regulation of AC9 by protein kinase C (PKC). Specifically, phorbol ester activation of PKC significantly attenuated (approximately 50%) Galpha(s)-stimulated AC9 activity. The effect of PKC activation on AC9 was reversed by the PKC inhibitor bisindolylmaleimide. Galpha(s)-stimulated cyclic accumulation was reduced more by simultaneous addition of both quinpirole and phorbol 12-myristate 13-acetate than by either drug alone. Additional studies investigated the role of glycosylation on AC9 activity. The results show that blocking glycosylation of AC9 significantly attenuates Galpha(s) stimulation. In contrast, the ability of PKC and Galpha(i/o) to negatively regulate AC9 did not seem to be affected by the glycosylation state of AC9. These observations demonstrate the diverse regulatory features of AC9 and the ability of AC9 to integrate multiple signals.
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Affiliation(s)
- Medhane G Cumbay
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana 47907, USA
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7
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da Silva Correia J, Ulevitch RJ. MD-2 and TLR4 N-linked glycosylations are important for a functional lipopolysaccharide receptor. J Biol Chem 2002; 277:1845-54. [PMID: 11706042 DOI: 10.1074/jbc.m109910200] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The lipopolysaccharide (LPS) receptor is a multi-protein complex that consists of at least three proteins, CD14, TLR4, and MD-2. Because each of these proteins is glycosylated, we have examined the functional role of N-linked carbohydrates of both MD-2 and TLR4. We demonstrate that MD-2 contains 2 N-glycosylated sites at positions Asn(26) and Asn(114), whereas the amino-terminal ectodomain of human TLR4 contains 9 N-linked glycosylation sites. Site-directed mutagenesis studies showed that cell surface expression of MD-2 did not depend on the presence of either N-linked site, whereas in contrast, TLR4 mutants carrying substitutions in Asn(526) or Asn(575) failed to be transported to the cell surface. Using a UV-activated derivative of Re595 LPS (ASD-Re595 LPS) in cross-linking assays, we demonstrated a critical role of MD-2 and TLR4 carbohydrates in LPS cross-linking to the LPS receptor. The ability of the various glycosylation mutants to support cell activation was also evaluated in transiently transfected HeLa cells. The double mutant of MD-2 failed to support LPS-induced activation of an interleukin-8 (IL-8) promoter-driven luciferase reporter to induce IL-8 secretion or to activate amino-terminal c-Jun kinase (JNK). Similar results were observed with TLR4 mutants lacking three or more N-linked glycosylation sites. Surprisingly, the reduction in activation resulting from expression of the Asn mutants of MD-2 and TLR4 can be partially reversed by co-expression with CD14. This suggests that the functional integrity of the LPS receptor depends both on the surface expression of at least three proteins, CD14, MD-2, and TLR4, and that N-linked sites of both MD-2 and TLR4 are essential in maintaining the functional integrity of this receptor.
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Affiliation(s)
- Jean da Silva Correia
- Scripps Research Institute, Department of Immunology, La Jolla, California 92037, USA
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8
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Nakagawa M, Miyamoto T, Kusakabe R, Takasaki S, Takao T, Shichida Y, Tsuda M. O-Glycosylation of G-protein-coupled receptor, octopus rhodopsin. Direct analysis by FAB mass spectrometry. FEBS Lett 2001; 496:19-24. [PMID: 11343699 DOI: 10.1016/s0014-5793(01)02392-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In addition to the N-glycan that is evidently conserved in G-protein-coupled receptors (GPCRs), O-glycans in the N-terminus of GPCRs have been suggested. Using a combination of enzymatic and manual Edman degradation in conjunction with G-protein coupled receptor mass spectrometry, the structure and sites of O-glycans in octopus rhodopsin are determined. Two N-acetylgalactosamine residues are O-linked to Thr4 and Thr5 in the N-terminus of octopus rhodopsin. Further, we found chicken iodopsin, but not bovine rhodopsin, contains N-acetylgalactosamine. This is the first direct evidence to determine the structure and sites of O-glycans in GPCRs.
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Affiliation(s)
- M Nakagawa
- Department of Life Sciences, Himeji Institute of Technology, Harima Science Garden City, Hyogo, Japan
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9
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Chotani MA, Flavahan S, Mitra S, Daunt D, Flavahan NA. Silent alpha(2C)-adrenergic receptors enable cold-induced vasoconstriction in cutaneous arteries. Am J Physiol Heart Circ Physiol 2000; 278:H1075-83. [PMID: 10749700 DOI: 10.1152/ajpheart.2000.278.4.h1075] [Citation(s) in RCA: 179] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cold constricts cutaneous blood vessels by increasing the reactivity of smooth muscle alpha(2)-adrenergic receptors (alpha(2)-ARs). Experiments were performed to determine the role of alpha(2)-AR subtypes (alpha(2A)-, alpha(2B)-, alpha(2C)-ARs) in this response. Stimulation of alpha(1)-ARs by phenylephrine or alpha(2)-ARs by UK-14,304 caused constriction of isolated mouse tail arteries mounted in a pressurized myograph system. Compared with proximal arteries, distal arteries were more responsive to alpha(2)-AR activation but less responsive to activation of alpha(1)-ARs. Cold augmented constriction to alpha(2)-AR activation in distal arteries but did not affect the response to alpha(1)-AR stimulation or the level of myogenic tone. Western blot analysis demonstrated expression of alpha(2A)- and alpha(2C)-ARs in tail arteries: expression of alpha(2C)-ARs decreased in distal compared with proximal arteries, whereas expression of the glycosylated form of the alpha(2A)-AR increased in distal arteries. At 37 degrees C, alpha(2)-AR-induced vasoconstriction in distal arteries was inhibited by selective blockade of alpha(2A)-ARs (BRL-44408) but not by selective inhibition of alpha(2B)-ARs (ARC-239) or alpha(2C)-ARs (MK-912). In contrast, during cold exposure (28 degrees C), the augmented response to UK-14,304 was inhibited by the alpha(2C)-AR antagonist MK-912, which selectively abolished cold-induced amplification of the response. These experiments indicate that cold-induced amplification of alpha(2)-ARs is mediated by alpha(2C)-ARs that are normally silent in these cutaneous arteries. Blockade of alpha(2C)-ARs may prove an effective treatment for Raynaud's Phenomenon.
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Affiliation(s)
- M A Chotani
- Heart and Lung Institute, Ohio State University, Columbus, Ohio 43210, USA
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10
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Izevbigie EB, Bergen WG. Beta-adrenergic agonist hyperplastic effect is associated with increased fibronectin gene expression and not mitogen-activated protein kinase modulation in C2C12 cells. PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE. SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE (NEW YORK, N.Y.) 2000; 223:302-9. [PMID: 10719844 DOI: 10.1046/j.1525-1373.2000.22343.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Beta-adrenergic agonists (beta-AA) enhance protein accretion in skeletal muscles. This stimulation is characterized by increased protein synthesis, increased expression of myofibrillar protein genes and a depression in protein degradation in animals, and increased proliferation and DNA synthesis in muscle cells in vitro. The mechanism or signal path in muscle whereby beta-AA would elicit these physiological effects upon binding to the G protein-coupled beta-adrenergic receptor (beta-AR) is unclear. C2C12 myoblasts were used to determine beta-AR ligand binding characteristics, cyclic AMP synthesis in response to isoproterenol (ISO) stimulation, and effects of ISO on DNA synthesis, mitogen activated protein kinase (MAPK), and fibronectin (FN) gene expression. Results showed that C2C12 cells possess beta-AR which are specific, saturable, and of high affinity (Kd = 0.2 nM). Forskolin and ISO stimulated cAMP production by = 20-fold (P<0.001) and 17-fold (P<0.001), respectively. ISO and the cAMP analog, 8-bromo-cAMP (8-BC) stimulated DNA synthesis in proliferating cells by 150% (P<0.05) and 200% (P<0.01), respectively, without modulating MAPK activity, whereas addition of fetal bovine serum to culture resulted in a 500% increase (P<0.01) in DNA synthesis and MAPK activation. DNA synthesis in C2C12 cells treated with ISO, 8-BC, or FBS was abolished in the presence of 25 microM PD098059, an MAPK-kinase inhibitor, suggesting that an MAPK-dependent pathway is likely involved in C2C12 proliferation. During cAMP elevating agent stimulation, basal MAPK activity may be sufficient, in the presence of other putative signaling molecules, to support proliferation in these cells. ISO or 8-BC treatment increased FN mRNA by three- and seven-fold, respectively, in growing C2C12 cells implying a connection between increased DNA synthesis and FN gene expression.
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Affiliation(s)
- E B Izevbigie
- Children's National Medical Center, Washington, DC 20010, USA
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11
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Schulte T, Kurrle R, Röllinghoff M, Gessner A. Molecular characterization and functional analysis of murine interleukin 4 receptor allotypes. J Exp Med 1997; 186:1419-29. [PMID: 9348299 PMCID: PMC2199121 DOI: 10.1084/jem.186.9.1419] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The murine interleukin 4 receptor (IL-4R) exists as a transmembrane protein transducing pleiotropic IL-4 functions, or as soluble (s)IL-4-binding molecule with potent immunoregulatory effects. In this study we identified and characterized a murine IL-4R allotype. Sequence analysis of the IL-4R cDNA of BALB/c mice revealed 18 base substitutions leading to three extracellular and five cytoplasmic amino acid changes when compared with the published IL-4R sequence of C57BL/6 mice. Analyses with allotype-specific mAbs revealed that AKR/J and SJL/J mice possess the newly identified BALB/c IL-4R allotype whereas the IL-4Rs of C3H, CBA, DBA-2, and FVB/N mice are identical to that of the C57BL/6 mouse. The extracellular Thr49 to Ile substitution abrogates one N-glycosylation site in the naturally occurring BALB/c IL-4R as well as in the experimentally point mutated C57BL/6-T49I sIL-4R, and both molecules display a nearly threefold reduction in IL-4-neutralizing activity compared to the C57BL/6 sIL-4R. In line with this, a significantly enhanced dissociation rate of IL-4 was detected for the BALB/c IL-4R allotype by surface plasmon resonance and in radioligand binding studies with IL-4R-transfected cell lines. These findings suggest that the altered ligand binding behavior of the newly described IL-4R allotype may influence the IL-4 responsiveness, thus contributing to the diverse phenotypes of inbred mouse strains in IL-4-dependent diseases.
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MESH Headings
- Alleles
- Amino Acid Substitution/genetics
- Animals
- Antibodies, Monoclonal/chemistry
- Antibody Specificity/genetics
- Base Sequence
- Binding Sites, Antibody/genetics
- Cell Membrane/metabolism
- DNA Restriction Enzymes
- Epitope Mapping
- Extracellular Space/chemistry
- Extracellular Space/immunology
- Female
- Glycosylation
- Kinetics
- Mice
- Mice, Inbred AKR
- Mice, Inbred BALB C
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Inbred DBA
- Mice, SCID
- Receptors, Interleukin-4/chemistry
- Receptors, Interleukin-4/genetics
- Receptors, Interleukin-4/immunology
- Receptors, Interleukin-4/metabolism
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Affiliation(s)
- T Schulte
- Institute of Clinical Microbiology and Immunology, University of Erlangen-Nürnberg, 91054 Erlangen, Germany
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12
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Jahns R, Siegmund C, Jahns V, Reiländer H, Maidhof A, Müller-Esterl W, Lohse MJ, Boege F. Probing human beta1- and beta2 -adrenoceptors with domain-specific fusion protein antibodies. Eur J Pharmacol 1997; 334:115-26. [PMID: 9346338 DOI: 10.1016/s0014-2999(97)80346-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In order to generate antibodies suitable for immunological studies on beta-adrenoceptors constitutively expressed at low levels in cells or tissues we have produced fusion proteins of the amino- and carboxy-terminus, and the second extracellular loop of the human beta1- or beta2-adrenoceptors with bacterial glutathione-S-transferase in E. coli. Rabbit antibodies raised against these fusion proteins strongly reacted with intact human beta1- or beta2-adrenoceptors in a subtype- and domain-specific manner. Antibodies directed against the second extracellular loop of the beta1-adrenoceptor reacted stronger with non-denatured receptors and decreased the affinity of the 3H-labelled antagonist (-)-4-(3-t-butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazol-2-one ([3H]CGP 12 177), indicating a specific interaction with the native receptor. In contrast, antibodies directed against carboxy- and amino-terminal receptor domains reacted strongly both with denatured and non-denatured receptors but did not interfere with binding of [3H]CGP 12 177. Affinity purified antibodies were used for detecting the beta1- or the beta2-adrenoceptor subtype heterologously produced in Sf9 cells by enzyme-linked immunosorbent assay, Western blotting, immunoprecipitation, and indirect immunofluorescence microscopy. Moreover, we could demonstrate that avidity, titers, and specificity of these antibodies were high enough for studying beta-adrenoceptors constitutively expressed in human A431 cells, where we observed a patched membrane distribution of the receptors.
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MESH Headings
- Animals
- Antibodies/immunology
- Antibody Specificity
- Blotting, Western
- Enzyme-Linked Immunosorbent Assay/methods
- Fluorescent Antibody Technique, Indirect
- Humans
- Precipitin Tests
- Rabbits
- Receptors, Adrenergic, beta-1/chemistry
- Receptors, Adrenergic, beta-1/immunology
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/immunology
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/immunology
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Affiliation(s)
- R Jahns
- Department of Pharmacology, University of Würzburg, Germany.
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13
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Rajaniemi HJ, Petäjä-Repo UE, Pietilä EM. Structure and functional significance of the carbohydrates of the LH/CG receptor. Mol Cell Endocrinol 1996; 125:101-5. [PMID: 9027348 DOI: 10.1016/s0303-7207(97)81879-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The LH/CG appears to contain 1-4 bi- or multi-antennary complex-type N-linked oligosaccharide side chains, which appear to locate apart from the hormone-binding regions. The exact sites to which the N-linked chains are attached remain to be delineated. The carbohydrates of the mature membrane-inserted receptor do not contribute to either specific high-affinity ligand-binding or signal transduction of the receptor. Thus, the polypeptide core of the receptor is responsible for both high affinity binding and dictating the hormone specificity. Moreover, the deglycosylated receptor, once inserted to the plasma membrane in a functionally mature form, retains its functional conformation or permits the conformational change that is required for coupling of the receptor to effector enzymes. Addition of oligosaccharides to the nascent LH/CG receptor but not their subsequent conversion to complex-type ones appears to be required for acquiring the hormone-binding conformation. On the other hand, neither addition of oligosaccharides to the nascent receptor, nor their further maturation are needed for the transport of the receptor to the plasma membrane. Thus, one function of the N-linked oligosaccharides in the LH/CG receptor appears to be to direct the proper folding of the receptor.
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14
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Jahns R, Siegmund C, Jahns V, Reiländer H, Maidhof A, Müller-Esterl W, Lohse MJ, Boege F. Probing human beta 1- and beta 2-adrenoceptors with domain-specific fusion protein antibodies. Eur J Pharmacol 1996; 316:111-21. [PMID: 8982658 DOI: 10.1016/s0014-2999(96)00654-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In order to generate antibodies suitable for immunological studies on beta-adrenoceptors constitutively expressed at low levels in cells or tissues we have produced fusion proteins of the amino- and carboxy-terminus, and the second extracellular loop of the human beta 1- or beta 2-adrenoceptors with bacterial glutathione-S-transferase in E. coli. Rabbit antibodies raised against these fusion proteins strongly reacted with intact human beta 1- or beta 2-adrenoceptors in a subtype- and domain-specific manner. Antibodies directed against the second extracellular loop of the beta 1-adrenoceptor reacted stronger with non-denatured receptors and decreased the affinity of the 3H-labelled antagonist (-)-4-(3-t-butylamino-2-hydroxypropoxy)-[5,7-3H]benzimidazol-2-one ([3H]CGP 12 177), indicating a specific interaction with the native receptor. In contrast, antibodies directed against carboxy- and amino-terminal receptor domains reacted strongly both with denatured and non-denatured receptors but did not interfere with binding of [3H]CGP 12 177. Affinity purified antibodies were used for detecting the beta 1- or the beta 2-adrenoceptor subtype heterologously produced in Sf9 cells by enzyme-linked immunosorbent assay, Western blotting, immunoprecipitation, and indirect immunofluorescence microscopy. Moreover, we could demonstrate that avidity, titers, and specificity of these antibodies were high enough for studying beta-adrenoceptors constitutively expressed in human A431 cells, where we observed a patched membrane distribution of the receptors.
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Affiliation(s)
- R Jahns
- Department of Pharmacology, University of Würzburg, Germany.
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15
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Helmreich EJ, Hofmann KP. Structure and function of proteins in G-protein-coupled signal transfer. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1286:285-322. [PMID: 8982287 DOI: 10.1016/s0304-4157(96)00013-5] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- E J Helmreich
- Department of Clinical Biochemistry and Pathobiochemistry, University of Würzburg, Germany
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16
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Pak MD, Fishman PH. Anomalous behavior of CGP 12177A on beta 1-adrenergic receptors. J Recept Signal Transduct Res 1996; 16:1-23. [PMID: 8771528 DOI: 10.3109/10799899609039938] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
CGP 12177A originally was developed as a hydrophilic antagonist to detect cell surface beta 1- and beta 2-adrenergic receptors, and subsequently was found to be a partial agonist for the atypical or beta 3-adrenergic receptor. Using hamster cells stably expressing either the human beta 1-, human beta 2- or rat beta 1-adrenergic receptor, we found that CGP 12177A behaved as an agonist of beta 1-adrenergic receptors. Whereas at low concentrations, CGP 12177a behaved as an antagonist and inhibited isoproterenol stimulation of adenylyl cyclase activity, at higher concentrations, it stimulated a response even in the absence of isoproterenol. The agonistic properties of CGP 12177A were positively correlated with the level of beta 1-adrenergic receptor expression. Thus, at low receptor of densities, CGP 12177A behaved as a weak, partial agonist whereas as high receptor densities, the drug was a full agonist. At similar high densities of the beta 2-adrenergic receptor, CGP 12177A acted only as a partial agonist. Competition binding studies to membranes from cells expressing beta 1-adrenergic receptors indicated that approximately 90% of the receptors were in a high affinity, guanine nucleotide-insensitive state for CGP 12177A whereas approximately 10% of the receptors were in a lower affinity, guanine nucleotide-sensitive state for CGP 12177A. We propose that the latter receptors are precoupled to stimulatory G proteins and recognize CGP 12177A as an agonist whereas the high affinity, uncoupled receptors recognize CGP 12177A as an antagonist.
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Affiliation(s)
- M D Pak
- Membrane Biochemistry Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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17
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Heithier H, Hallmann D, Boege F, Reiländer H, Dees C, Jaeggi KA, Arndt-Jovin D, Jovin TM, Helmreich EJ. Synthesis and properties of fluorescent beta-adrenoceptor ligands. Biochemistry 1994; 33:9126-34. [PMID: 7914090 DOI: 10.1021/bi00197a015] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We describe the synthesis of bordifluoropyrromethene (BODIPY), fluorescein, and related fluorescent derivatives of the beta-adrenergic ligand CGP 12177. With these probes we screened insect (Sf9) cells stably transformed with the human beta 2-adrenoceptor gene and expressing (2-3.5) x 10(5) human beta 2-adrenoceptors per cell. Among these derivatives only BODIPY-CGP gave a receptor-specific signal sufficiently strong for measuring the on- and off-rate constants and the equilibrium dissociation constant of beta-adrenoceptor-specific binding by spectrofluorometry or photon counting. Similar KD values for BODIPY-CGP binding were obtained by kinetic measurements (approx. 250 pM) and under equilibrium conditions (400 +/- 180 pM), and these were in the same range as those obtained with [3H]CGP 12177 (200 +/- 32 pM). The cell-bound fluorescence could be quenched specifically with nonfluorescent CGP 12177 to near background levels. The disposition of the beta 2-adrenoceptors in BODIPY-CGP-stained Sf9 cells was mainly restricted to the cell surface at 4 and 30 degrees C. Hence, beta-adrenoceptor-expressing cells can be stained specifically with BODIPY-CGP, and beta-adrenoceptors on a single cell can be assessed by photon counting under the fluorescence microscope. Cells can also be scanned by fluorescence-activated flow cytometry.
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Affiliation(s)
- H Heithier
- Medizinische Universitätsklinik, Abteilung für Klinische Biochemie und Pathobiochemie, Würzburg, Germany
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18
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Lis H, Sharon N. Protein glycosylation. Structural and functional aspects. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 218:1-27. [PMID: 8243456 DOI: 10.1111/j.1432-1033.1993.tb18347.x] [Citation(s) in RCA: 572] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
During the last decade, there have been enormous advances in our knowledge of glycoproteins and the stage has been set for the biotechnological production of many of them for therapeutic use. These advances are reviewed, with special emphasis on the structure and function of the glycoproteins (excluding the proteoglycans). Current methods for structural analysis of glycoproteins are surveyed, as are novel carbohydrate-peptide linking groups, and mono- and oligo-saccharide constituents found in these macromolecules. The possible roles of the carbohydrate units in modulating the physicochemical and biological properties of the parent proteins are discussed, and evidence is presented on their roles as recognition determinants between molecules and cells, or cell and cells. Finally, examples are given of changes that occur in the carbohydrates of soluble and cell-surface glycoproteins during differentiation, growth and malignancy, which further highlight the important role of these substances in health and disease.
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Affiliation(s)
- H Lis
- Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel
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19
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Kleymann G, Boege F, Hahn M, Hampe W, Vasudevan S, Reiländer H. Human beta 2-adrenergic receptor produced in stably transformed insect cells is functionally coupled via endogenous GTP-binding protein to adenylyl cyclase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 213:797-804. [PMID: 8386637 DOI: 10.1111/j.1432-1033.1993.tb17822.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Spodoptera frugiperda insect cells (Sf9) containing the stably integrated human beta 2-adrenergic receptor gene under the control of the baculovirus IE1 promoter expressed up to 350,000 human receptors/cell. The number of receptors did not change with cell density or age of culture. The adrenergic receptors overexpressed in the insect cells were functional with respect to their ligand binding and signalling properties. Coupling of the receptors to endogenous GTP-binding proteins is demonstrated by hormone-dependent stimulation of GTPase and adenylyl cyclase activity in the transformed insect cells. Western-blot analysis revealed that the endogenous GTP-binding protein appears to be of the heterotrimeric type. Antibodies raised against the mammalian alpha subunit of stimulatory GTP-binding proteins cross-react with the insect alpha subunit of GTP-binding proteins, which also exhibits the same apparent molecular mass as its mammalian counterpart. The beta subunit of GTP-binding proteins from insect cells reacts with anti-peptide serum directed against the C-terminal amino acids of the mammalian beta subunit of GTP-binding proteins, but is about approximately 2 kDa larger than that of the beta subunit of GTP-binding proteins from bovine brain. Exposure of the transformed insect cells to L-isoproterenol rapidly induces uncoupling and internalization of 30% of the heterologously expressed receptors. In contrast to the situation in mammalian cells, prolonged exposure of the agonist (24 h) does not result in down regulation of the remaining 70% of the receptors.
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Affiliation(s)
- G Kleymann
- Max-Planck-Institut für Biophysik, Abt. Molekulare Membranbiologie, Frankfurt/M, Germany
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20
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Doyle JW, Ward-Bailey PF, Kandutsch AA. Effects of growth factors on cell cycle arrest in dolichyl phosphate-depleted cultures. J Cell Physiol 1993; 155:171-8. [PMID: 8468363 DOI: 10.1002/jcp.1041550122] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Previously we showed that CHO cell growth is arrested in the G1 or G0 phase within 24 h after the biosynthesis of mevalonic acid is blocked. The growth-limiting factor under these conditions appeared to be dolichyl phosphate or one of its glycosylated derivatives with consequent decrease in the synthesis of N-linked glycoproteins (Doyle, J.W., and A.A. Kandutsch, 1988, J. Cell Physiol. 137:133-140; Kabakoff, B., J.W. Doyle, and A.A. Kandutsch, 1990, Arch. Biochem. Biophys. 276:382-389). We show herein that cell surface glycoproteins are depleted in the inhibited cultures and that growth arrest is delayed when supraphysiological concentrations of insulin, insulin-like growth factor-1 (IGF-1) and bFGF are added to the culture medium. Apparently an elevated level of a growth factor increases the length of time during which a threshold level of occupied receptor is maintained as the number of glycosylated receptor molecules declines. The results support the idea that cellular levels of dolichyl phosphate and its derivatives may limit cell division by controlling the numbers of functional receptors for growth factors and of other glycoproteins on the cell surface.
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Affiliation(s)
- J W Doyle
- Jackson Laboratory, Bar Harbor, Maine 04609-0800
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21
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Gomez J, Benovic JL. Molecular and regulatory properties of the adenylyl cyclase-coupled beta-adrenergic receptors. INTERNATIONAL REVIEW OF CYTOLOGY 1993; 137B:1-34. [PMID: 1336003 DOI: 10.1016/s0074-7696(08)62598-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- J Gomez
- Department of Pharmacology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19107
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22
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Chen YC, Smith JB. A putative lectin-binding receptor mediates cadmium-evoked calcium release. Toxicol Appl Pharmacol 1992; 117:249-56. [PMID: 1471158 DOI: 10.1016/0041-008x(92)90244-m] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Nanomolar concentrations of cadmium (Cd2+) produce an immediate rise in free Ca2+ in human dermal fibroblasts, which is mostly caused by the release of stored Ca2+ via inositol trisphosphate. Here we have used lectins to evaluate the hypothesis that a cell surface glycoprotein mediates the response to Cd2+. A prior incubation with wheat germ agglutinin (WGA) or certain other lectins inhibited calcium release evoked by Cd2+. WGA reversibly inhibited Cd(2+)-evoked calcium release as indicated by measurements of cytosolic free Ca2+ and 45Ca2+ efflux. WGA half-maximally inhibited Ca2+ release at 1.2 x 10(-7) M. The Kd for the binding of fluoresceinylated WGA was 2.8 x 10(-7) M. Chitotriose dissociated fluoresceinylated WGA from the cells and restored cadmium responsiveness. WGA inhibited Cd(2+)-evoked 45Ca2+ efflux similarly at 18 and 37 degrees C. A brief incubation with chitotriose at 18 or 10 degrees C reversed the inhibition by WGA. WGA neither bound 109Cd2+ nor affected 109Cd2+ uptake by the cells. Succinylated WGA, which binds N-acetylglucosamine but not N-acetylneuraminic acid, failed to inhibit Ca2+ release evoked by Cd2+. WGA probably inhibits Ca2+ release produced by Cd2+ by binding to N-acetylneuraminic acid in the external domain of a plasma membrane receptor.
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Affiliation(s)
- Y C Chen
- Department of Pharmacology, School of Medicine, University of Alabama, Birmingham 35294
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23
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Fountoulakis M, Gentz R. Effect of Glycosylation on Properties of Soluble Interferon Gamma Receptors Produced in Prokaryotic and Eukaryotic Experession Systems. Nat Biotechnol 1992; 10:1143-7. [PMID: 1368793 DOI: 10.1038/nbt1092-1143] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We investigated the influence of glycosylation on solubility, chromatographic behavior and resistance to heat- and chaotrope-dependent denaturation and proteolytic digestion of three recombinant human interferon gamma receptors produced in Escherichia coli, Spodoptera frugiperda and Chinese hamster ovary cells. The proteins produced in the eukaryotic expression systems were glycosylated, carrying different, heterogeneous carbohydrate moieties. They were assayed fully glycosylated and after removal of the oligosaccharides. Although glycosylation influenced the chromatographic behavior of the tested proteins, it did not protect against proteolysis and heat- or chaotrope-induced denaturation. The glycosylated receptors were slightly more sensitive to certain proteolytic cleavages and slightly less resistant to chaotropes, than the soluble receptor produced in Escherichia coli.
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Affiliation(s)
- M Fountoulakis
- F. Hoffmann-La Roche Ltd., Pharmaceutical Research-New Technologies, Basel, Switzerland
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24
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Lew R, Patel A, Vaughan RA, Wilson A, Kuhar MJ. Microheterogeneity of dopamine transporters in rat striatum and nucleus accumbens. Brain Res 1992; 584:266-71. [PMID: 1515945 DOI: 10.1016/0006-8993(92)90905-o] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Previously we have shown that the [125I]DEEP-labeled dopamine transporter from the rat nucleus accumbens has a higher apparent molecular weight than that from striatum. The present study confirms and extends these observations. Experiments with nucleus accumbens showed [125I]-DEEP to specifically bind to a protein with an apparent molecular weight of 76 kDa and with the pharmacological properties of the dopamine transporter. In exoglycosidase studies, treatment with neuraminidase, but not alpha-mannosidase, reduced the apparent molecular weight of the dopamine transporter from both the striatum and nucleus accumbens; however, a difference in the apparent molecular weight was still observed. N-Glycanase treatment, on the other hand, did reduce the apparent molecular weight of the dopamine transporters from the two regions to a similar value, approximately 56 kDa. In radioligand binding studies examining the effect of partial deglycosylation on striatal dopamine transporters, neuraminidase did not affect specific [3H]WIN 35,428 binding at 4 and 40 nM concentrations. In conclusion, the present study demonstrates that the difference in the apparent molecular weight of the dopamine transporter from these two regions is due to a difference in glycosylation and that the dopamine transporter from both regions contains similar amounts of sialic acid in their carbohydrate structure. Furthermore, the present data also indicate that the polypeptide portion of the dopamine transporter from both regions could be the same gene product.
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Affiliation(s)
- R Lew
- Neuroscience Branch, NIDA Addiction Research Center, Baltimore, MD 21224
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25
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Jans DA, Jans P, Luzius H, Fahrenholz F. N-glycosylation plays a role in biosynthesis and internalization of the adenylate cyclase stimulating vasopressin V2-receptor of LLC-PK1 renal epithelial cells: an effect of concanavalin A on binding and expression. Arch Biochem Biophys 1992; 294:64-9. [PMID: 1532296 DOI: 10.1016/0003-9861(92)90137-l] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The role of N-glycosylation in the function and biosynthesis of the vasopressin V2-receptor in LLC-PK1 renal epithelial cells was examined using various lectins and inhibitors operating at different steps of the glycosidic pathway. Tunicamycin, which blocks all N-glycosylation, and castanospermine, which inhibits glycosidase I and hence blocks formation of high-mannose-type N-glycosylated intermediates, resembled one another in affecting V2-receptor biosynthesis and internalization in a concentration-dependent manner. In contrast, swainsonine, an inhibitor of mannosidase II and hence of complex-type oligosaccharide formation, had no effect. Interestingly, the alpha-D-mannose/alpha-D-glucose-specific lectin concanavalin A, (Con A), in contrast to the beta-D-galactose-specific lectin ricin, had a marked effect on the V2-receptor in LLC-PK1 cells, increasing both receptor numbers up to twofold in vivo and specific [3H]AVP binding up to 50% in vitro in a concentration-dependent manner. The concentrations inducing half-maximal response were about 0.2 and 20 micrograms/ml for the in vivo and in vitro responses, respectively, implying distinct effects on V2-expression and ligand binding. That the in vitro effect on binding was due to a direct effect on the V2-receptor could be shown by the lack of a Con A effect on [3H]AVP binding in membranes prepared from LLC-PK1 cells down-regulated for the V2-receptor or from cells of the LLC-PK1 V2-receptor deficient mutant M18. All results were consistent with a functional role for N-glycosylation of the V2-receptor in LLC-PK1 cells.
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Affiliation(s)
- D A Jans
- Max-Planck-Institut für Biophysik, Frankfurt am Main, FRG
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26
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Howlett AC, Champion-Dorow TM, McMahon LL, Westlake TM. The cannabinoid receptor: biochemical and cellular properties in neuroblastoma cells. Pharmacol Biochem Behav 1991; 40:565-9. [PMID: 1806946 DOI: 10.1016/0091-3057(91)90364-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The cannabinoid receptor that has been pharmacologically characterized for hypothermia, spontaneous activity, analgesia and catalepsy in rodents is the same pharmacological receptor that inhibits adenylate cyclase in vitro. The inhibition of adenylate cyclase by the cannabinoid receptor results from an interaction with Gi, based on the biochemical kinetic properties of the response, the sensitivity to pertussis toxin ADP-ribosylation, and the thermodynamic characteristics of the response. From precedents based on studies of the well-characterized G protein coupled receptors, rhodopsin and the beta-adrenergic receptor, we can predict the tertiary structure of the cannabinoid receptor. Three sites of potential glycosylation are present on the receptor. However, treatment of N18TG2 neuroblastoma cells with tunicamycin to prevent glycosylation of newly synthesized receptors failed to alter cannabinoid-induced inhibition of cyclic AMP accumulation. The cannabinoid response was rapidly desensitized (within 1/2 h). Treatment of cells with tunicamycin failed to alter agonist-induced desensitization processes. These findings can be more veraciously interpreted as we gain a better understanding of the cellular dynamics of the cannabinoid receptor.
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Affiliation(s)
- A C Howlett
- Department of Pharmacological and Physiological Science, St. Louis University Medical School, MO 63104
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27
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Buck F, Meyerhof W, Werr H, Richter D. Characterization of N- and C-terminal deletion mutants of the rat serotonin HT2 receptor in Xenopus laevis oocytes. Biochem Biophys Res Commun 1991; 178:1421-8. [PMID: 1872857 DOI: 10.1016/0006-291x(91)91052-e] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Deletion mutants of the serotonin HT2 receptor have been constructed in which the N- and C-terminal sequences have been gradually removed. The mutant constructs were assayed for their biological activity by electrophysiological measurements in Xenopus oocytes previously injected with the respective in vitro synthesized cRNAs. No significant loss of biological activity was observed when either the extracellular N-terminal sequence, including all potential glycosylation sites, up to the beginning of the first transmembrane domain or the C-terminal sequence up to cystein residue 397, which is conserved in most G-protein coupled receptor known so far, was deleted from the serotonin HT2 receptor constructs.
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Affiliation(s)
- F Buck
- Institut für Zellbiochemie, UKE, Universität Hamburg, Hamburg, Germany
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28
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Boege F, Neumann E, Helmreich EJ. Structural heterogeneity of membrane receptors and GTP-binding proteins and its functional consequences for signal transduction. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 199:1-15. [PMID: 1648482 DOI: 10.1111/j.1432-1033.1991.tb16085.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recent information obtained, mainly by recombinant cDNA technology, on structural heterogeneity of hormone and transmitter receptors, of GTP-binding proteins (G-proteins) and, especially, of G-protein-linked receptors is reviewed and the implications of structural heterogeneity for diversity of hormone and transmitter actions is discussed. For the future, three-dimensional structural analysis of membrane proteins participating in signal transmission and transduction pathways is needed in order to understand the molecular basis of allosteric regulatory mechanisms governing the interactions between these proteins including hysteretic properties and cell-cybernetic aspects.
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Affiliation(s)
- F Boege
- Department of Physiological Chemistry, University of Würzburg, Federal Republic of Germany
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29
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Reiländer H, Boege F, Vasudevan S, Maul G, Hekman M, Dees C, Hampe W, Helmreich EJ, Michel H. Purification and functional characterization of the human beta 2-adrenergic receptor produced in baculovirus-infected insect cells. FEBS Lett 1991; 282:441-4. [PMID: 1645288 DOI: 10.1016/0014-5793(91)80532-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A human cDNA fragment bearing the complete coding region for the beta 2-adrenergic receptor was introduced into the genome of Autographa california nuclear polyhedrosis virus under the control of the polyhedrin promoter. Binding studies using [125I]iodocyanopindolol showed that Sf9 insect cells infected with the recombinant virus expressed approximately 1 x 10(6) beta 2-adrenergic receptors on their cell surface. Photoaffinity labeling of whole cells and membranes revealed a molecular weight of approximately 46,000 for the expressed receptor. The receptor produced in insect cells is glycosylated but the extent and pattern differ from that of the receptor from human tissue. The heterologously expressed receptor was purified by alprenolol affinity chromatography, and was able to activate isolated Gs-protein.
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Affiliation(s)
- H Reiländer
- Max Planck Institut für Biophysik, Frankfurt, Germany
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30
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Parker E, Ross E. Truncation of the extended carboxyl-terminal domain increases the expression and regulatory activity of the avian beta-adrenergic receptor. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92917-0] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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31
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Kurstjens NP, Fröhlich M, Dees C, Cantrill RC, Hekman M, Helmreich EJ. Binding of alpha- and beta gamma-subunits of Go to beta 1-adrenoceptor in sealed unilamellar lipid vesicles. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 197:167-76. [PMID: 1849815 DOI: 10.1111/j.1432-1033.1991.tb15895.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
First, we describe a preparation of sealed unilamellar lipid vesicles. When this preparation was subjected to sucrose density gradient centrifugation, two rather uniform fractions emerged, one consisting of lighter lipid-rich vesicles with average diameters ranging over 150-200 nm (fraction I), the other consisting of heavier vesicles with average diameters ranging over 30-70 nm (fraction II). When the lipid mixture containing dimyristoylglycerophosphocholine, cholesterol, dipalmitoylglycerophosphoserine and dipalmitoylglycerophosphoethanolamine at molar ratios of 54:35:10:1 was reconstituted with alpha- and beta gamma-subunits of Go-proteins purified to homogeneity from bovine brain, the lipid-rich lighter vesicle fraction I took up these subunits nearly exclusively. Whereas, when a beta 1-adrenoceptor preparation purified from turkey erythrocyte membranes was reconstituted, it was found nearly completely in the smaller heavier vesicle fraction II where it was incorporated inside-out. On co-reconstitution of either alpha o or beta gamma alone with beta 1-adrenoceptors, some of these subunits appear together with beta 1-adrenoceptors in the small vesicle fraction II, but much more alpha o was bound to the receptor in the presence of beta gamma-subunits. The observations reported are novel and surprising in several respects: firstly, they suggest that beta gamma-subunits can bind to the non-activated beta 1-receptor where they may serve as an anchor for alpha-subunits. Secondly, the binding of alpha o- and beta gamma-subunits to the beta 1-adrenoceptors enhances the basal GTPase activity of alpha o. Thirdly, since the binding domains of the beta 1-adrenoceptor for G-proteins were facing outwards in our sealed vesicle preparations, it follows that interactions of G-proteins with the beta-receptor can occur at the aqueous membrane interface as was postulated originally by M. Chabre [Trends Biochem. Sci. 12, 213-215 (1987)] for the transducin-rhodopsin interactions. Finally, the binding of Go-subunits from bovine brain to a beta 1-adrenoceptor from turkey erythrocytes was not expected, since these polypeptides are not likely to be physiological partners.
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Affiliation(s)
- N P Kurstjens
- Physiologisch-Chemisches Institut der Universität Würzburg, Federal Republic of Germany
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32
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Parker EM, Kameyama K, Higashijima T, Ross EM. Reconstitutively active G protein-coupled receptors purified from baculovirus-infected insect cells. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52467-4] [Citation(s) in RCA: 222] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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33
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Wang HY, Berrios M, Hadcock JR, Malbon CC. The biology of beta-adrenergic receptors: analysis in human epidermoid carcinoma A431 cells. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1991; 23:7-20. [PMID: 1850702 DOI: 10.1016/0020-711x(91)90003-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
1. G-protein-linked transmembrane signaling has emerged as a major pathway for information transduction across the cell membrane. 2. In addition to photopigments that propagate the signal from light, cell-surface receptors for hormones, neurotransmitters, and autacoids propagate signals from ligand binding to membrane-bound effector units via G-proteins. 3. Biochemical and molecular features of one prominent member of these receptors, the beta-adrenergic receptor, will be highlighted in the present article. 4. The role of the human epidermoid carcinoma A431 cells as a model for the study of the structure and biology of beta-adrenergic receptors will be emphasized. 5. A model for receptor regulation, gleaned from recent advances in the biochemistry, cell and molecular biology of beta-adrenergic receptors, is discussed.
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Affiliation(s)
- H Y Wang
- Department of Biochemistry, National Defence Medical Center, Taipei, Taiwan, Republic of China
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34
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Abstract
Application of a molecular genetic techniques has allowed the isolation and identification of more than 50 members of the G protein-coupled receptor family. Their specificities range from sensory receptors such as the opsins and odorant receptors through those for the amines, peptides and other small molecules to those for glycoprotein hormones. These studies make it clear that traditional pharmacological methods, often underestimate receptor diversity. G protein-coupled receptors share a common structure consisting of 7 transmembrane alpha helical segments. Receptor structure-function relationships are discussed in the light of results obtained by site-directed mutagenesis and the construction of chimeric receptors. Studies which have allowed the identification of ligand-binding domains, and of sequences defining G protein specificity as well as those involved in receptor desensitization and downregulation are also discussed.
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Affiliation(s)
- T Jackson
- Department of Biochemistry, AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, U.K
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35
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van Koppen CJ, Nathanson NM. Site-directed mutagenesis of the m2 muscarinic acetylcholine receptor. Analysis of the role of N-glycosylation in receptor expression and function. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45299-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Rands E, Candelore MR, Cheung AH, Hill WS, Strader CD, Dixon RA. Mutational analysis of beta-adrenergic receptor glycosylation. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)87012-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Kurstjens NP, Heithier H, Cantrill RC, Hahn M, Boege F. Multiple hormone actions: the rises in cAMP and Ca++ in MDCK-cells treated with glucagon and prostaglandin E1 are independent processes. Biochem Biophys Res Commun 1990; 167:1162-9. [PMID: 1690994 DOI: 10.1016/0006-291x(90)90645-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Glucagon and prostaglandin E1 stimulate adenylate cyclase in Madin-Darby canine kidney cells with an approximate EC50 of 3*10(-8) and 1*10(-7) M respectively. The rise in cAMP is accompanied by a transient rise in intracellular Ca++ measured with the fluorescent calcium indicator Indo-1. A comparable increase in intracellular Ca2+ without a rise in cAMP occurs with the cholinergic agonist carbamylcholine. Stimulation of adenylate cyclase by the beta-adrenergic agonist isoproterenol or directly by forskolin has no effect on intracellular Ca++. By all criteria studied the rise in intracellular Ca++ and the increase in cAMP are independent from each other.
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Affiliation(s)
- N P Kurstjens
- Department of Physiological Chemistry, University of Würzburg Medical School, F.R.G
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Yatsunami K, Fujisawa J, Hashimoto H, Kimura K, Takahashi S, Ichikawa A. Effect of tunicamycin on functions of PGE1 receptors from mouse mastocytoma P-815 cells. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1051:94-9. [PMID: 2153417 DOI: 10.1016/0167-4889(90)90178-g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Prostaglandin E1 (PGE1) receptors from mouse mastocytoma P-815 cells were found to bind to a wheat germ agglutinin (WGA)-Agarose column, suggesting that the receptors are glycoproteins. To further elucidate the role of carbohydrate moieties in the PGE1 receptors for their binding activity to ligand, the P-815 cells were treated with tunicamycin, swainsonine or monensin. Tunicamycin, an inhibitor of N-glycosylation, dose- and time-dependently inhibited the binding of PGE1 to mastocytoma P-815 cells. Neither swainsonine, an inhibitor of Golgi mannosidase II, nor monensin, an inhibitor of processing beyond the high mannose stage, altered PGE1 binding properties of the cells. The inhibition of PGE1 binding by tunicamycin was observed when incorporation of [3H]glucosamine into macromolecules was inhibited. The inhibitory effect was not on their affinity but on their number of binding sites. Subcellular distributions of [3H]PGE1-binding activity showed that decreases in the binding activity by tunicamycin were highest in plasma membrane fractions. Treatment of membranes with various endo- and exoglycosidases did not affect PGE1 binding. PGE1-stimulated cyclic AMP accumulation in the cells was also inhibited by tunicamycin. These results suggest that PGE1 receptors of mastocytoma P-815 cells are glycoproteins and that inhibition of N-glycosylation of PGE1 receptors by tunicamycin results in the arrest of the translocation of newly synthesized receptors to the surface of mastocytoma P-815 cells.
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Affiliation(s)
- K Yatsunami
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
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Glycosylation of the human interferon-gamma receptor. N-linked carbohydrates contribute to structural heterogeneity and are required for ligand binding. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)40074-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Affiliation(s)
- R D Cummings
- Department of Biochemistry, University of Georgia, Athens 30602
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