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Coura RS, Cressant A, Xia J, de Chaumont F, Olivo-Marin JC, Pelloux Y, Dalley JW, Granon S. Nonaggressive and adapted social cognition is controlled by the interplay between noradrenergic and nicotinic receptor mechanisms in the prefrontal cortex. FASEB J 2013; 27:4343-54. [PMID: 23882123 PMCID: PMC3977319 DOI: 10.1096/fj.13-231084] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 06/24/2013] [Indexed: 02/02/2023]
Abstract
Social animals establish flexible behaviors and integrated decision-making processes to adapt to social environments. Such behaviors are impaired in all major neuropsychiatric disorders and depend on the prefrontal cortex (PFC). We previously showed that nicotinic acetylcholine receptors (nAChRs) and norepinephrine (NE) in the PFC are necessary for mice to show adapted social cognition. Here, we investigated how the cholinergic and NE systems converge within the PFC to modulate social behavior. We used a social interaction task (SIT) in C57BL/6 mice and mice lacking β2*nAChRs (β2(-/-) mice), making use of dedicated software to analyze >20 social sequences and pinpoint social decisions. We performed specific PFC NE depletions before SIT and measured monoamines and acetylcholine (ACh) levels in limbic corticostriatal circuitry. After PFC-NE depletion, C57BL/6 mice exhibited impoverished and more rigid social behavior and were 6-fold more aggressive than sham-lesioned animals, whereas β2(-/-) mice showed unimpaired social behavior. Our biochemical measures suggest a critical involvement of DA in SIT. In addition, we show that the balance between basal levels of monoamines and of ACh modulates aggressiveness and this modulation requires functional β2*nAChRs. These findings demonstrate the critical interplay between prefrontal NE and nAChRs for the development of adapted and nonaggressive social cognition.
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Affiliation(s)
- Renata S Coura
- 3Centre de Neuroscience Paris Sud, UMR 8195, Université Paris Sud, Orsay, 91405.
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dos Santos Coura R, Granon S. Prefrontal neuromodulation by nicotinic receptors for cognitive processes. Psychopharmacology (Berl) 2012; 221:1-18. [PMID: 22249358 DOI: 10.1007/s00213-011-2596-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Accepted: 11/17/2011] [Indexed: 11/30/2022]
Abstract
RATIONALE The prefrontal cortex (PFC) mediates executive functions, a set of control processes that optimize performance on cognitive tasks. It enables appropriate decision-making and mediates adapted behaviors, all processes impaired in psychiatric or degenerative disorders. Key players of normal functioning of the PFC are neurotransmitter (NT) systems arising from subcortical nuclei and targeting PFC subareas and, also, neuronal nicotinic acetylcholine receptors (nAChRs). These ion channels, located on multiple cell compartments in all brain areas, mediate direct cholinergic transmission and modulate the release of NTs that cross onto PFC neurons or interneurons. OBJECTIVE We compiled current knowledge concerning the role of nAChRs in NT release, focusing on the PFC. We point out plausible mechanisms of interaction among PFC circuits implicated in executive functions and emphasized the role of β2-containing nAChRs, the high-affinity receptors for acetylcholine (ACh). These receptors are more directly implicated in behavioral flexibility either when located on PFC neurons or in the monoaminergic or cholinergic systems targeting the PFC. RESULTS We shed light on potentially crucial roles played by nAChRs in complex interactions between local and afferent NTs. We show how they could act on cognition via PFC networks. CONCLUSIONS nAChRs are crucial for decision-making, during integration of emotional and motivational features, both mediated by different NT pathways in the PFC. We review the knowledge recently gained on cognitive functions in mice and our current understanding of PFC NT modulation. The combination of these data is expected to provide new hypotheses concerning the role of AChRs in cognitive processes.
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CHANGEUX JEANPIERRE. THE VISIT OF PROFESSOR CHEN-YUAN LEE TO THE PASTEUR INSTITUTE IN 1970 AND THE USE OF A SNAKE VENOM TOXIN TO IDENTIFY THE ACETYLCHOLINE RECEPTOR PROTEIN. TOXIN REV 2008. [DOI: 10.1081/txr-200046237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Gottschalk A, Schafer WR. Visualization of integral and peripheral cell surface proteins in live Caenorhabditis elegans. J Neurosci Methods 2006; 154:68-79. [PMID: 16466809 DOI: 10.1016/j.jneumeth.2005.11.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2005] [Revised: 11/08/2005] [Accepted: 11/29/2005] [Indexed: 10/25/2022]
Abstract
To study the abundance of specific receptors and other cell surface proteins at synapses, it would be advantageous to specifically label these proteins only when inserted in the plasma membrane. We describe a method that allows to fluorescently label cell surface proteins in live and behaving animals, namely in the nematode Caenorhabditis elegans. Proteins such as subunits of the levamisole sensitive nicotinic acetylcholine receptor (nAChR) were epitope-tagged at their extracellular C-termini, and fluorescent antibodies against those tags were injected into the body fluid. These antibodies specifically labelled synaptic regions on the cell surface of muscles and neurons, and simultaneous use of different tags facilitated co-localization studies. Quantification of the fluorescence is possible, as verified by demonstrating that mutations in ric-3 and unc-38, which cause behavioural resistance to cholinergic agonists, strongly reduce or even abolish nAChR cell surface expression. We also used this method to visualize the extracellular peripheral membrane protein ODR-2, which is related to a neurotoxin-like protein regulating vertebrate neuronal nAChRs. Likewise, fluorescent alpha-bungarotoxin, when injected, bound to certain nAChRs in the pharynx and the nervous system. This showed that, theoretically, any molecular interaction of sufficient affinity may be used to specifically label cell surface structures in live nematodes.
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Affiliation(s)
- Alexander Gottschalk
- Department of Biochemistry, Chemistry and Pharmacy, Institute for Biochemistry, Biocenter N210, Johann Wolfgang Goethe-University, Frankfurt, Germany.
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Gottschalk A, Almedom RB, Schedletzky T, Anderson SD, Yates JR, Schafer WR. Identification and characterization of novel nicotinic receptor-associated proteins in Caenorhabditis elegans. EMBO J 2005; 24:2566-78. [PMID: 15990870 PMCID: PMC1176467 DOI: 10.1038/sj.emboj.7600741] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Accepted: 06/13/2005] [Indexed: 11/09/2022] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) mediate fast excitatory neurotransmission in neurons and muscles. To identify nAChR accessory proteins, which may regulate their expression or function, we performed tandem affinity purification of the levamisole-sensitive nAChR from Caenorhabditis elegans, mass spectrometry of associated components, and RNAi-based screening for effects on in vivo nicotine sensitivity. Among the proteins identified was the calcineurin A subunit TAX-6, which appeared to function as a negative regulator of nAChR activity. We also identified five proteins not previously linked to nAChR function, whose inactivation conferred nicotine resistance, implicating them as positive regulators of nAChR activity. Of these, the copine NRA-1 colocalized with the levamisole receptor at neuronal and muscle plasma membranes, and, when mutated, caused reduced synaptic nAChR expression. Loss of SOC-1, which acts in receptor tyrosine kinase (RTK) signaling, also reduced synaptic levamisole receptor levels, as did mutations in the fibroblast growth factor receptor EGL-15, and another RTK, CAM-1. Thus, tandem affinity purification is a viable approach to identify novel proteins regulating neurotransmitter receptor activity or expression in model systems like C. elegans.
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Affiliation(s)
- Alexander Gottschalk
- Institute for Biochemistry, Goethe-University, Frankfurt, Germany
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
- Institute for Biochemistry, Goethe-University, Biocenter N210, Marie-Curie-Str. 9, 60439 Frankfurt, Germany. Tel.: +49 69 798 29261; Fax: +49 69 798 29495; E-mail:
| | - Ruta B Almedom
- Institute for Biochemistry, Goethe-University, Frankfurt, Germany
| | | | - Scott D Anderson
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - John R Yates
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - William R Schafer
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
- Division of Biological Sciences, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0643, USA. Tel.: +1 858 822 0508; Fax: +1 858 822 2003; E-mail:
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Barrantes FJ. The lipid environment of the nicotinic acetylcholine receptor in native and reconstituted membranes. Crit Rev Biochem Mol Biol 1989; 24:437-78. [PMID: 2676352 DOI: 10.3109/10409238909086961] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Detailed knowledge of the membrane framework surrounding the nicotinic acetylcholine receptor (AChR) is key to an understanding of its structure, dynamics, and function. Recent theoretical models discuss the structural relationship between the AChR and the lipid bilayer. Independent experimental data on the composition, metabolism, and dynamics of the AChR lipid environment are analyzed in the first part of the review. The composition of the lipids in which the transmembrane AChR chains are inserted bears considerable resemblance among species, perhaps providing this evolutionarily conserved protein with an adequate milieu for its optimal functioning. The effects of lipids on the latter are discussed in the second part of the review. The third part focuses on the information gained on the dynamics of AChR and lipids in the membrane, a section that also covers the physical properties and interactions between the protein, its immediate annulus, and the bulk lipid bilayer.
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Affiliation(s)
- F J Barrantes
- Institute of Biochemistry, CONICET, Universidad Nac. del Sur, Bahia Blanca, Argentina
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Filbin MT, Lunt GG, Donnellan JF. Partial purification and characterisation of an acetylcholine receptor with nicotinic properties from the supraoesophageal ganglion of the locust (Schistocerca gregaria). EUROPEAN JOURNAL OF BIOCHEMISTRY 1983; 132:151-6. [PMID: 6840078 DOI: 10.1111/j.1432-1033.1983.tb07340.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
An alpha-bungarotoxin-binding component has been partially purified from the supraoesophageal ganglion of the locust, (Schistocerca gregaria). The component binds alpha-bungarotoxin with a Kd of about 1.7 nM and this value changes little throughout the purification procedure. The specific binding activity ranges from 1.18 pmol alpha-bungarotoxin bound/mg protein for the membrane-bound site up to a maximum of 230 pmol bound/mg protein for the partially purified component. The pharmacological properties of the membrane-bound site are predominantly nicotinic. Affinity labelling of the binding species with 4-(N-maleimido)-[3H]benzyltrimethylammonium suggests that the binding is associated with a peptide of Mr 58000. Polyacrylamide gel electrophoresis of the partially purified of binding component shows three major bands corresponding to Mr of 60000, 41000 and 25000. We suggest that the binding component can be tentatively identified as a nicotinic acetylcholine receptor.
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Barrantes FJ. Recent developments in the structure and function of the acetylcholine receptor. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1983; 24:259-341. [PMID: 6317598 DOI: 10.1016/s0074-7742(08)60224-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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The use of monoclonal antibodies to study the nicotinic acetylcholine receptor. Trends Pharmacol Sci 1982. [DOI: 10.1016/0165-6147(82)91155-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Peper K, Sterz R, Bradley RJ. Effects of drugs and antibodies on the post-synaptic membrane of the neuromuscular junction. Ann N Y Acad Sci 1981; 377:519-43. [PMID: 6978665 DOI: 10.1111/j.1749-6632.1981.tb33757.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Stephenson FA, Harrison R, Lunt GG. The isolation and characterisation of the nicotinic acetylcholine receptor from human skeletal muscle. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 115:91-7. [PMID: 7227375 DOI: 10.1111/j.1432-1033.1981.tb06202.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Nicotinic acetylcholine receptor protein has been purified from human skeletal muscle by a procedure involving extraction in non-ionic detergent followed by affinity purification on immobilised alpha-toxin. Purified receptor preparations had specific activities of 0.5-3.5 mumol alpha-bungarotoxin binding sites/g protein and sedimented as a single 125I-alpha-bungarotoxin-binding species in sucrose-density-gradient centrifugation with s20,w = 9.5 S. The purified protein focussed as a single sharp band at pH 5.1 when complexed to 125I-alpha-bungarotoxin. Polyacrylamide gel electrophoresis of the purified receptor under denaturing conditions showed two major protein bands with Mr 42 000 and 66 000 respectively with the occasional appearance of minor components of Mr 56 000 and 85 000. Only the 42 000-Mr band was labelled with the affinity reagent, 4-(N-maleimido)[3H]-benzyltrimethylammonium. The purified receptor bound 125I-alpha-bungarotoxin and d-tubocurarine with Kd values of 0.5 nM and 0.25 microM respectively. It behaved similarly to unpurified detergent-extracted human receptor in the radioimmunoassay for anti-(human acetylcholine receptor) antibodies and when injected into rabbits caused increased levels of the latter antibodies but did not cause experimental autoimmune myasthenia gravis.
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Montal M, Darszon A, Schindler H. Functional reassembly of membrane proteins in planar lipid bilayers. Q Rev Biophys 1981; 14:1-79. [PMID: 6269143 DOI: 10.1017/s0033583500002079] [Citation(s) in RCA: 102] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Recent progress in membrane biology has brought us to a stage where it is possible to associate complex biological processes to identifiable membrane proteins. Technical advances in the biochemical characterization and purification of membrane proteins have contributed a wealth of structural information. The reconstitution approach has proved to be valuable in our efforts to understand the molecular mechanisms of membrane transport and energy transduction.
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Sobel A, Heidmann T, Cartaud J, Changeux JP. Reconstitution of a functional acetylcholine receptor. Polypeptide chains, ultrastructure, and binding sites for acetylcholine and local anesthetics. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 110:13-33. [PMID: 7439153 DOI: 10.1111/j.1432-1033.1980.tb04838.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The 'reconstitution cycle' is composed of the following sequence of operations. Highly purified receptor-rich membranes prepared from Torpedo marmorata electric organ are exposed to pH 11 to remove the 43,000-Mr protein and dispersed into solution by sodium cholate under conditions where more than 85% of the receptor protein is in its 9-S form. Elimination of the detergent by filtration on a Sephadex column (or dialysis) yields a 'reconstituted receptor' fraction, under conditions which conserve part of the endogenous lipids, or 'reconstituted vesicles' in the presence of an excess of exogenous lipids. The polypeptide composition of these fractions was analysed by sodium dodecylsulfate gel electrophoresis. Conditions are defined for quantitative measurements of the various polypeptide chains. The 40,000-Mr chain, which is labelled by the affinity reagent 4-(N-maleimido)phenyl [3H]trimethylammonium and therefore carries the acetylcholine receptor site, is the dominant polypeptide in the alkaline-treated membranes and the reconstituted acetylcholine receptor. Electron microscopy discloses that many of the alkaline-treated membranes no longer form closed vesicles and do not show the transverse asymmetry of the native membranes observed after tannic acid fixation. In the reconstituted receptor fractions, the receptor molecules reaggregate into discs and may be exposed on both faces of the discs. In the reconstituted vesicles, receptor rosettes are integrated to the lipid vesicles. With native membranes, the radioactive local anesthetic [3H]trimethisoquin binds to three classes of sites: non-specific, low-affinity and high-affinity. Carbamylcholine causes an increase in the number of high-affinity sites up to approximately 0.7 times the number of alpha-125I-bungarotoxin sites. This ratio, the three classes of binding sites, and their regulation by carbamylcholine are conserved through the reconstitution cycle.
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Purification of acetylcholine receptors, reconstitution into lipid vesicles, and study of agonist-induced cation channel regulation. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)70652-8] [Citation(s) in RCA: 132] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Heidmann T, Sobel A, Popot JL, Changeux JP. Reconstitution of a functional acetylcholine receptor. Conservation of the conformational and allosteric transitions and recovery of the permeability response; role of lipids. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 110:35-55. [PMID: 7439162 DOI: 10.1111/j.1432-1033.1980.tb04839.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The 'functional' state of the acetylcholine receptor protein has been followed during reconstitution with the fluorescent agonist [1-(5-dimethylaminonaphthalene)-sulfonamidol]-n-hexanoic acid-beta-N-trimetylammonium bromide ethyl ester (Dns-C6-Cho) and rapid-mixing techniques. Under appropriate conditions, a majority of the acetylcholine receptor sites can be recovered in a low-affinity state(s) for Dns-C6-Cho, similar to that found with the native membrane-bound receptor. This state can be slowly interconverted to a high-affinity state after rapid mixing with the agonist, and the non-competitive channel blockers, like the local anesthetics, still regulate this transition in an allosteric manner. Several experimental conditions commonly used for the solubilization of the receptor and for its purification in the presence of sodium cholate result in the failure of reconstitution: the soluble receptor protein is stabilized in a low-affinity state which can no longer be interconverted to a high-affinity state in the presence of agonists or local anesthetics. On the other hand, it is demonstrated that if the concentration of lipids remains elevated in the presence of sodium cholate, a soluble (9-S) low-affinity form of the receptor protein can be obtained which shows most of the characteristic properties of the membrane-bound receptor and in particular the slow interconversion to the high-affinity state and the effect of local anesthetics on this transition; furthermore, in these conditions the soluble protein can be manipulated ad libitum and submitted, for instance, to column filtrations and sucrose gradient centrifugations in the presence of detergent, without losing its characteristic conformational and allosteric transitions. After elimination of the detergent this form yields a reconstituted receptor which presents binding properties identical to those of the native membrane-bound receptor and leads to the formation of vesicles which exhibit carbamylcholine-sensitive ion fluxes. A necessary and sufficient condition for functional reconstitution is therefore the conservation, in the presence of lipids, of the allosteric properties of the receptor protein in its detergent-soluble form.
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Ochoa EL. The incorporation of acetylcholinesterase from the electric organ into liposomes. EUROPEAN JOURNAL OF BIOCHEMISTRY 1980; 107:415-21. [PMID: 7398650 DOI: 10.1111/j.1432-1033.1980.tb06045.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Several methods have been used to bind electric organ aetylcholinesterase to the walls of phosphatidylcholine liposomes. One of these methods [Brunner, J., Skrabal, P. & Hauser, H. (1976) Biochim. Biophys. Acta, 455, 322-331] achieved complete incorporation, although some enzyme was shown to be sequestered inside the vesicles. The association was established either in the presence of high salt media or altered liposomal membrane fluidity. The reconstitution process impaired the allosteric transition of acetylcholinesterase which is thought to occur when Flaxedil (gallamine triethiodide) is present in a low ionic strength medium. It is suggested that the cholinesterase is capable of being incorporated into liposomes, possibly via hydrophobic forces. Such a system may be an adequate one for further study of the functioning of the enzyme in a defined membrane environment.
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Nelson N, Anholt R, Lindstrom J, Montal M. Reconstitution of purified acetylcholine receptors with functional ion channels in planar lipid bilayers. Proc Natl Acad Sci U S A 1980; 77:3057-61. [PMID: 6930685 PMCID: PMC349546 DOI: 10.1073/pnas.77.5.3057] [Citation(s) in RCA: 111] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Acetylcholine receptor, solubilized and purified from Torpedo californica electric organ under conditions that preserve the activity of its ion channel, was reconstituted into vesicles of soybean lipid by the cholate-dialysis technique. The reconstituted vesicles were then spread into monolayers at an air-water interface and planar bilayers were subsequently formed by apposition of two monolayers. Addition of carbamoylcholine caused an increase in membrane conductance that was transient and relaxed spontaneously to the base level (i.e., became desensitized). The response to carbamoylcholine was dose dependent and competitively inhibited by curare. Fluctuations of membrane conductance corresponding to the opening and closing of receptor channels were observed. Fluctuation analysis indicated a single-channel conductance of 16 +/- 3 pS (in 0.1 M NaCl) with a mean channel open time estimated to be 35 +/- 5 ms. Thus, purified acetylcholine receptor reconstituted into lipid bilayers exhibited the pharmacological specificity, activation, and desensitization properties expected of this receptor in native membranes.
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Criteria for the Reconstitution of Ion Transport Systems. ACTA ACUST UNITED AC 1980. [DOI: 10.1016/s0070-2161(08)60115-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Changeux JP, Heidmann T, Popot JL, Sobel A. Reconstitution of a functional acetylcholine regulator under defined conditions. FEBS Lett 1979; 105:181-7. [PMID: 488341 DOI: 10.1016/0014-5793(79)80913-8] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Heidmann T, Sobel A, Changeux JP. Recovery of allosteric interactions between a fluorescent cholinergic agonist and local anesthetics after removal of the detergent from cholate-solubilized membrane fragments rich in acetylcholine receptor. FEBS Lett 1978; 94:397-404. [PMID: 568082 DOI: 10.1016/0014-5793(78)80986-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Popot JL, Demel RA, Sobel A, Van Deenen LL, Changeux JP. Interaction of the acetylcholine (nicotinic) receptor protein from Torpedo marmorata electric organ with monolayers of pure lipids. EUROPEAN JOURNAL OF BIOCHEMISTRY 1978; 85:27-42. [PMID: 639821 DOI: 10.1111/j.1432-1033.1978.tb12209.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Membrane fragments rich in cholinergic (nicotinic) receptor protein were purified from the electric organ of Torpedo marmorata. Their lipid composition is essentially characterized by the prominence of cholesterol, phosphatidylethanolamine and phosphatidylcholine, long-chain fatty acyl constituents, and the absence of sphingomyelin. Solubilised receptor was purified from these fragments and the concentration of sodium cholate lowered by dialysis to 0.01% (w/v). When this preparation was injected under a lipid monolayer, an increase of surface pressure developed, which was not observed with the detergent alone nor in the absence of lipid film. When covalently radiolabelled receptor preparations were injected at a constant surface pressure the radioactivity recovered with the film was proportional to the increase in area. It is concluded that the pressure or area increases are due to the penetration of the cholinergic receptor protein into the lipid film. Incorporation experiments into films formed from various pure lipids showed that the protein interacts more readily with cholesterol than with ergosterol, phosphatidylcholine, or other phospholipids. Its affinity is also higher for long-chain phosphatidylcholines than for short-chain ones. The degree of unsaturation and fluidity of the 3-sn-phosphatidylcholine (lecithin) films are of secondary importance. Parallel experiments with covalently and non-covalently labelled receptor preparations showed that part of the protein recovered with the film lost its alpha-toxin binding ability during the penetration. Similar data were obtained with the receptor purified from Electrophorus electricus electric organ.
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Briley MS, Changeux JP. Recovery of some functional properties of the detergent-extracted cholinergic receptor protein from Torpedo marmorata after reintegration into a membrane environment. EUROPEAN JOURNAL OF BIOCHEMISTRY 1978; 84:429-39. [PMID: 565286 DOI: 10.1111/j.1432-1033.1978.tb12184.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The change of affinity of the acetylcholine receptor for agonists and the influence of local anaesthetics has been studied in detail in receptor-rich membranes. These properties are changed after solubilisation by ionic detergents. A method for reproducibly reintegrating the receptor protein into a lipid environment is described. Reintegration of the receptor results in partial recovery of the binding and fluorescence properties of the membrane-bound receptor protein. In particular, the slow affinity change caused by agonists can be recovered but not the effect of local anaesthetics on this change. The fluorescence response to cholinergic ligands of the reintegrated receptor protein labelled with quinacrine does not appear identical to that found with the native receptor-rich membranes. It is suggested that the failure to recover the sensitivity to local anaesthetics is at the origin of the difficulties to regain functional reconstitution.
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