In order to study where the binding site of cholinergic agents is in the sequence of the alpha-subunit of nicotinic acetylcholine receptor (AChR), we have synthetized 3 peptides with an amino acid sequence corresponding to the following sequences of the alpha-subunit of Torpedo californica AChR: 125-143, 158-167, [Lys] 188-201. For binding studies the peptides were immobilized on Sepharose 4B. Only the peptide [Lys] 188-201 binds 125I-alpha-bungarotoxin (alpha-Bgtx) with Kd of 1.03 microM. The binding of 125I-alpha-Bgtx to the peptide is reduced by 85% after reduction of the S-S bridge present between 192-193 cysteines indicating that an intact disulfide bond is important for toxin binding. The 125I-alpha-Bgtx binding is inhibited by curare, decamethonium, hexamethonium but not by carbamylcholine and Naja naja siamensis alpha-toxin and P15 toxin. All these data provide direct evidence that the sequence 188-201 of the alpha-subunit of AChR binds alpha-Bgtx and that this binding has a pharmacological profile similar to that of nicotinic acetylcholine receptor.

The binding site for alpha-bungarotoxin resides in the sequence 188-201 of the alpha-subunit of acetylcholine receptor: structure, conformation and binding characteristics of peptide [Lys] 188-201 / C. Gotti, G. Mazzola, R. Longhi, D. Fornasari, F. Clementi. - In: NEUROSCIENCE LETTERS. - ISSN 0304-3940. - 82:1(1987 Nov 10), pp. 113-119.

The binding site for alpha-bungarotoxin resides in the sequence 188-201 of the alpha-subunit of acetylcholine receptor: structure, conformation and binding characteristics of peptide [Lys] 188-201

D. Fornasari
Penultimo
;
F. Clementi
Ultimo
1987-11-10

Abstract

In order to study where the binding site of cholinergic agents is in the sequence of the alpha-subunit of nicotinic acetylcholine receptor (AChR), we have synthetized 3 peptides with an amino acid sequence corresponding to the following sequences of the alpha-subunit of Torpedo californica AChR: 125-143, 158-167, [Lys] 188-201. For binding studies the peptides were immobilized on Sepharose 4B. Only the peptide [Lys] 188-201 binds 125I-alpha-bungarotoxin (alpha-Bgtx) with Kd of 1.03 microM. The binding of 125I-alpha-Bgtx to the peptide is reduced by 85% after reduction of the S-S bridge present between 192-193 cysteines indicating that an intact disulfide bond is important for toxin binding. The 125I-alpha-Bgtx binding is inhibited by curare, decamethonium, hexamethonium but not by carbamylcholine and Naja naja siamensis alpha-toxin and P15 toxin. All these data provide direct evidence that the sequence 188-201 of the alpha-subunit of AChR binds alpha-Bgtx and that this binding has a pharmacological profile similar to that of nicotinic acetylcholine receptor.
Acetylcholine receptor; Cholinergic binding site; Cholinergic ligand; Naja naja siamensis α-toxin; P15 toxin; α-Bungarotoxin
Settore BIO/14 - Farmacologia
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/179393
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