Structural determinants of alpha-bungarotoxin binding to the sequence segment 181-200 of the muscle nicotinic acetylcholine receptor. alpha. subunit: Effects of cysteine/cystine modification and species-specific amino acid substitution

Journal Article · Tue May 21 00:00:00 EDT 1991 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00234a013· OSTI ID:5014378

McLane, K E; Wu, Xiadong; Diethelm, B; Conti-Tronconi, B M ^[1]

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1. Univ. of Minnesota, St. Paul (United States)

The sequence segment 181-200 of the Torpedo nicotinic acetylcholine receptor (nAChR) {alpha}subunit forms a binding site for {alpha}-bungarotoxin ({alpha}-BTX). Synthetic peptides corresponding to the homologous sequences of human, calf, mouse, chicken, frog, and cobra muscle nAChR {alpha}1 subunits were tested for their ability to bind {sup 125}I-{alpha}-BTX, and differences in {alpha}-BTX affinity were determined by using solution (IC{sub 50}s) and solid-phase (K{sub d}s) assays. Panels of overlapping peptides corresponding to the complete {alpha}1 subunit of mouse and human were also tested for {alpha}-BTX binding, but other sequence segments forming the {alpha}-BTX site were not consistently detectable. The role of a putative vicinal disulfide bound between Cys-192 and -193, relative to the Torpedo sequence, was determined by modifying the peptides with sulfhydryl reagents. Reduction and alkylation of the peptides decreased {alpha}-BTX binding, whereas oxidation of the peptides had little effect. These results indicate that while the adjacent cysteines are likely to be involved in forming the toxin/{alpha}1-subunit interface a vicinal disulfide bound was not required for {alpha}-BTX binding.

• OSTI ID: 5014378
• Journal Information: Biochemistry; (United States), Vol. 30:20; ISSN 0006-2960
• Country of Publication: United States
• Language: English

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