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Crotoxin effects on Torpedo californica cholinergic excitable vesicles and the role of its phospholiphase A activity

Journal Article · · Biochem. Biophys. Res. Commun.; (United States)
The phospholipolytic neurotoxin from Crotalus durissus terrificus, crotoxin, is able to produce a dose- and time-dependent block of carbachol-stimulated /sup 22/Na efflux from pre-loaded Torpedo californica excitable vesicles. The blocking activity is dependent on calcium and is abolished by chemical modification with p-bromophenacyl bromide. The isolated basic subunit, crotoxin B, produces an identical block, whereas the isolated acidic subunit, crotoxin A, has no detectable effect. Neither crotoxin nor crotoxin B antagonizes the binding of (/sup 125/I)-..cap alpha..-bungarotoxin to purified acetylcholine receptor, although, at high concentrations, they antagonize its binding to acetylcholine receptor-rich membrane fragments. Certain phospholipase A/sub 2/ enzymes and the fatty acid products of their digestion can mimic the crotoxin action. It is therefore suggested that, although considered a pre-synaptic neurotoxin, crotoxin can have in vitro post-synaptic effects, possibly mediated by its endogeneous phospholipase A/sub 2/ activity.
Research Organization:
Univ. of California, Berkeley
OSTI ID:
5099403
Journal Information:
Biochem. Biophys. Res. Commun.; (United States), Journal Name: Biochem. Biophys. Res. Commun.; (United States) Vol. 82:1; ISSN BBRCA
Country of Publication:
United States
Language:
English

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