Mapping of a cholinergic binding site by means of synthetic peptides, monoclonal antibodies, and. alpha. -bungarotoxin

Journal Article · Tue Jul 03 00:00:00 EDT 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00478a016· OSTI ID:6290721

Conti-Tronconi, B M; Tang, Fen; Diethelm, B M; Spencer, S R ^[1]; Reinhardt-Maelicke, S; Maelicke, A ^[2]

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1. Univ. of Minnesota, St. Paul (USA)
2. Max-Planck-Institut fur Ernahrungsphysiologie, Dortmund (West Germany)

Previous studies by several laboratories have identified a narrow sequence region of the nicotinic acetylcholine receptor (AChR) {alpha} subunit, flanking the cysteinyl residues at positions 192 and 193, as containing major elements of, if not all, the binding site for cholinergic ligands. In the present study, the authors used a panel of synthetic peptides as representative structural elements of the AChR to investigate whether additional segments of the AChR sequences are able to bind {alpha}-bungarotoxin ({alpha}-BTX) and several {alpha}-BTX-competitive monoclonal antibodies (mAbs). The mAbs used (WF6, WF5, and W2) were raised against native Torpedo AChR, specifically recognize the {alpha}-subunit, and bind to AChR in a mutually exclusive fashion with {alpha}-BTX. The binding of WF5 and W2 to Torpedo AChR is inhibited by all cholinergic ligands. WF6 competes with agonists, but not with low mol. wt. antagonists, for AChR binding. Peptides {alpha}181-200 and {alpha}55-74 both inhibited binding of {sup 125}I-{alpha}-BTX to native Torpedo AChR. None of the peptides corresponding to sequence segments from other subunits bound {alpha}-BTX or WF6, or interfered with their binding. Therefore, the cholinergic binding site is not a single narrow sequence region, but rather two or more discontinuous sequence segments within the N-terminal extracellular region of the AChR {alpha} subunit, folded together in the native structure of the receptor, contribute to form a cholinergic binding region.

• OSTI ID: 6290721
• Journal Information: Biochemistry; (USA), Vol. 29:26; ISSN 0006-2960
• Country of Publication: United States
• Language: English

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