Paper Report for: Lacorazza_1996_Neurochem.Int_28_557
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Title: Localization of histidine residues relevant for the binding of alpha-bungarotoxin to the acetylcholine receptor alpha-subunit in V8-proteolytic fragments Lacorazza HD, Lopez RA, Venera GD, Biscoglio de Jimenez Bonino M Ref: Neurochem Int, 28:557, 1996 : PubMed
Histidine residues have been shown to be critical for alpha-BgTx binding to the acetylcholine receptor (Lacorazza et al., 1992; Bouzat et al., 1993; Lacorazza et al., 1995). Receptor subunits from Discopyge tschudii were modified with diethylpyrocarbonate (DEP). DEP treatment produces a concentration-dependent decrease of [125I] alpha-BgTx binding to the alpha-subunit. The neurotoxin binding capacity was fully restored by adding the nucleophile hydroxylamine. By proteolytic mapping of the alpha-subunit with V8-protease, we determined that the binding capacity to the fragment alpha V8-19 decreased 80% by DEP treatment. In addition, the [125I] alpha-BgTx binding to the same fragment decreased by 70% when the subunits were reduced and affinity-alkylated. We report the N-terminal sequence of both subunits and V8-fragments (alpha V8-10, alpha V8-13, and alpha V8-18), which constitute a first contribution to the knowledge of the primary structure of the Discopyge tschudii receptor. We propose that the fragment alpha V8-19 contains one or more of the histidine residues involved in the alpha-BgTx binding and probably includes the Cys alpha 192-193 disulfide bond. Only two histidine residues are present in the extracellular sequence of Torpedo californica for such fragments: His alpha 186 and alpha 204.
        
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Lacorazza HD, Lopez RA, Venera GD, Biscoglio de Jimenez Bonino M (1996) Localization of histidine residues relevant for the binding of alpha-bungarotoxin to the acetylcholine receptor alpha-subunit in V8-proteolytic fragments Neurochem Int28: 557-67
Lacorazza HD, Lopez RA, Venera GD, Biscoglio de Jimenez Bonino M (1996) Neurochem Int28: 557-67