Conformational effects of volatile anesthetics on the membrane-bound acetylcholine receptor protein: facilitation of the agonist-induced affinity conversion

Biochemistry ◽  
1983 ◽  
Vol 22 (9) ◽  
pp. 2155-2162 ◽  
Author(s):  
Anthony P. Young ◽  
David S. Sigman
Keyword(s):  
Acetylcholine Receptor ◽  
Volatile Anesthetics ◽  
Receptor Protein ◽  
Conformational Effects ◽  
Membrane Bound

A simple quantitative assay of 125I-labeled α-bungarotoxin binding to soluble and membrane-bound acetylcholine receptor protein

1977 ◽  
Vol 80 (2) ◽  
pp. 531-539 ◽  
Author(s):  
Ronald A. Kohanski ◽  
John P. Andrews ◽  
Pierre Wins ◽  
Mohyee E. Eldefrawi ◽  
George P. Hess
Keyword(s):  
Acetylcholine Receptor ◽  
Quantitative Assay ◽  
Receptor Protein ◽  
Membrane Bound

Acetylcholine receptor protein structure

1978 ◽  
Vol 36 (2) ◽  
pp. 180-181
Author(s):  
A. Brisson
Keyword(s):  
Acetylcholine Receptor ◽  
Conformational Changes ◽  
Binding Sites ◽  
Particle Surface ◽  
Cholinergic Receptor ◽  
Transmission Mechanism ◽  
Receptor Protein ◽  
Subunit Structure ◽  
Structural Relationships ◽  
Membrane Bound

The acetylcholine receptor protein plays a leading part in the synaptic transmission mechanism. The binding of the neurotransmitter, acetylcholine, to the protein triggers conformational changes, allowing the translocation of ions through the membrane. The structural relationships between the binding sites of the cholinergic ligands and the translocating part of the protein are still unknown, as the subunit composition is. A better knowledge of the structure of the acetylcholine receptor protein is the aim of the present study.Negatively stained preparations of purified cholinergic receptor protein and of membrane fragments rich in acetylcholine receptor protein are characterized by the presence of particles having a diameter of 8-9 mm, and exhibiting a doughnut like structure, with a central pit filled with stain. The variability in the stain distribution on the particle surface did'nt allow to determine the subunit structure of the protein. In the case of crystalline biological specimens, methods of averaging have allowed to overcome this problem; then, we have tried to crystallize the membrane-bound cholinergic receptor protein.

scholarly journals Oligomeric forms of the membrane-bound acetylcholine receptor disclosed upon extraction of the M(r) 43,000 nonreceptor peptide

1982 ◽  
Vol 92 (1) ◽  
pp. 60-68 ◽  
Author(s):  
FJ Barrantes
Keyword(s):  
Acetylcholine Receptor ◽  
Receptor Protein ◽  
Antigenic Determinants ◽  
Torpedo Marmorata ◽  
Carbon Supports ◽  
Nitrobenzoic Acid ◽  
Particle Aggregates ◽  
Membrane Bound ◽  
Monospecific Antibodies ◽  
Oligomeric Forms

Oligomeric forms of the acetylcholine receptor are directly visualized by electron microscopy in receptor-rich membranes from torpedo marmorata. The receptor structures are quantitatively correlated with the molecular species so far identified only after detergent solubilization, and further related to the polypeptide composition of the membranes and changes thereof. The structural identification is made possibly by the increased fragility of the membranes after extraction of nonreceptor peptides and their subsequent disruption upon drying onto hydrophilic carbon supports. Receptor particles in native membranes depleted of nonreceptor peptides appear as single units of 7-8 nm, and double and multiple aggregates thereof. Particle doublets having a main-axis diameter of 19 +/- 3 nm predominate in these membranes. Linear aggregates of particles similar to those observed in rotary replicas of quick-frozen fresh electrolytes (Heuser, J.E. and S. R. Salpeter. 1979, J. Cell Biol. 82: 150-173) are also present in the alkaline-extracted membranes. Chemical modifications of the thiol groups shift the distribution of structural species. Dithiothreitol reduction, which renders almost exclusively the 9S, monomeric receptor form, results in the observation of the 7-8 nm particle in isolated form. The proportion of doublets increases in membranes alkylated with N-ethylmaleimide. Treatment with 5,5'-dithiobis-(nitrobenzoic acid) increases the proportion of higher oligomeric species, and particle aggregates (n=oligo) predominate. The nonreceptor v-peptide (doublet of M(r) 43,000) appears to play a role in the receptor monomer-polymer equilibria. Receptor protein and v-peptide co-aggregate upon reduction and reoxidation of native membranes. In membranes protected ab initio with N- ethylmaleimide, only the receptor appears to self-aggregate. The v-peptide cannot be extracted from these alkylated membranes, though it is easily released from normal, subsequently alkylated or reduced membranes. A stabilization of the dimeric species by the nonreceptor v-peptide is suggested by these experiments. Monospecific antibodies against the v-peptide are used in conjunction with rhodamine- labeled anti-bodies in an indirect immunoflourescence assay to map the vectorial exposure of the v-peptide. When intact membranes, v-peptide depleted and "holey" native membranes (treated with 0.3 percent saponin) are compared, maximal labeling is obtained with the latter type of membranes, suggesting a predominantly cytoplasmic exposure of the antigenic determinants of the v-peptide in the membrane. The influence of the v-peptide in the thiol-dependent interconversions of the receptor protein and the putative topography of the peptide are analyzed in the light of the present results.

Allosteric interactions between the membrane-bound acetylcholine receptor and chemical mediators. Kinetic studies

Biochemistry ◽  
1977 ◽  
Vol 16 (4) ◽  
pp. 684-692 ◽  
Author(s):  
James E. Bulger ◽  
Juian-Juian L. Fu ◽  
Ellen F. Hindy ◽  
Richard L. Silberstein ◽  
George P. Hess
Keyword(s):  
Acetylcholine Receptor ◽  
Kinetic Studies ◽  
Allosteric Interactions ◽  
Membrane Bound ◽  
Chemical Mediators
Sign in / Sign up

Export Citation Format

Share Document