Biomaterial Database

Antibody-induced conformational changes in the Torpedo nicotinic acetylcholine receptor: a fluorescence study. 1994

C F Valenzuela, and A J Dowding, and H R Arias, and D A Johnson

Division of Biomedical Sciences, University of California, Riverside 92521-0121.

Quantitative fluorescence spectroscopy was used to develop a structural picture of the effects of two monoclonal antibodies (mAbs) on the conformation of the Torpedo nicotinic acetylcholine receptor (nAChR). The two mAbs (A6 and B1) examined selectively blocked ligand binding to either the high-affinity (A) or the low-affinity (B) binding sites for agonists/competitive antagonists. The distances between dansyl-C6-choline bound to the unblocked agonist/competitive antagonist binding site and one of two lipophilic probes (C12-eosin or C18-rhodamine) partitioned into the lipid membrane were estimated by using fluorescence resonance energy transfer. Control experiments demonstrated that both mAbs decreased the affinity and fluorescence lifetime of receptor-bound dansyl-C6-choline. The binding of the B1 mAb to the B site did not significantly change the calculated distance between the unblocked A binding site and the membrane surface. However, the binding of the A6 mAb to the A site induced the B site to move into close proximity to the lipid membrane. This conformational change was confirmed by a 45-fold increase in the paramagnetic quenching of the B-site-bound dansyl-C6-choline fluorescence by lipid-intercalated 5-doxylstearate. The results indicate that these mAbs not only selectively block ligand binding to either the A or the B acetylcholine sites but also, in the case of the A6 mAb, induce global conformational changes of the receptor, which appear to involve a movement of the B binding site into close proximity of the lipid membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D011978	Receptors, Nicotinic	One of the two major classes of cholinergic receptors. Nicotinic receptors were originally distinguished by their preference for NICOTINE over MUSCARINE. They are generally divided into muscle-type and neuronal-type (previously ganglionic) based on pharmacology, and subunit composition of the receptors.	Nicotinic Acetylcholine Receptors,Nicotinic Receptors,Nicotinic Acetylcholine Receptor,Nicotinic Receptor,Acetylcholine Receptor, Nicotinic,Acetylcholine Receptors, Nicotinic,Receptor, Nicotinic,Receptor, Nicotinic Acetylcholine,Receptors, Nicotinic Acetylcholine
D002794	Choline	A basic constituent of lecithin that is found in many plants and animal organs. It is important as a precursor of acetylcholine, as a methyl donor in various metabolic processes, and in lipid metabolism.	Bursine,Fagine,Vidine,2-Hydroxy-N,N,N-trimethylethanaminium,Choline Bitartrate,Choline Chloride,Choline Citrate,Choline Hydroxide,Choline O-Sulfate,Bitartrate, Choline,Chloride, Choline,Choline O Sulfate,Citrate, Choline,Hydroxide, Choline,O-Sulfate, Choline
D003619	Dansyl Compounds	Compounds that contain a 1-dimethylaminonaphthalene-5-sulfonyl group.	Dimethylaminonaphthalenesulfonyl Compounds,Compounds, Dansyl,Compounds, Dimethylaminonaphthalenesulfonyl
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000911	Antibodies, Monoclonal	Antibodies produced by a single clone of cells.	Monoclonal Antibodies,Monoclonal Antibody,Antibody, Monoclonal
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D013050	Spectrometry, Fluorescence	Measurement of the intensity and quality of fluorescence.	Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D014101	Torpedo	A genus of the Torpedinidae family consisting of several species. Members of this family have powerful electric organs and are commonly called electric rays.	Electric Rays,Torpedinidae,Rays, Electric
D016513	Mice, SCID	Mice homozygous for the mutant autosomal recessive gene "scid" which is located on the centromeric end of chromosome 16. These mice lack mature, functional lymphocytes and are thus highly susceptible to lethal opportunistic infections if not chronically treated with antibiotics. The lack of B- and T-cell immunity resembles severe combined immunodeficiency (SCID) syndrome in human infants. SCID mice are useful as animal models since they are receptive to implantation of a human immune system producing SCID-human (SCID-hu) hematochimeric mice.	SCID Mice,SCID-hu Mice,Severe Combined Immunodeficient Mice,Immunodeficient Mice, Severe Combined,Mouse, SCID,Mouse, SCID-hu,Mice, SCID-hu,Mouse, SCID hu,SCID Mouse,SCID hu Mice,SCID-hu Mouse