Crotoxin effects on Torpedo californica cholinergic excitable vesicles and the role of its phospholipase A activity |
| |
Authors: | M R Hanley |
| |
Affiliation: | 1. Laboratory of Chemical Biodynamics, University of California, Berkeley, CA 94720 USA;2. Lawrence Berkeley Laboratory, University of California, Berkeley, CA 94720 USA;3. Department of Molecular Biology, University of California, Berkeley, CA 94720 USA |
| |
Abstract: | The phospholipolytic neurotoxin from , crotoxin, is able to produce a dose- and time-dependent block of carbachol-stimulated 22Na efflux from pre-loaded 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 to purified acetylcholine receptor, although, at high concentrations, they antagonize its binding to acetylcholine receptor-rich membrane fragments. Certain phospholipase A2 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 post-synaptic effects, possibly mediated by its endogeneous phospholipase A2 activity. |
| |
Keywords: | AChR acetylcholine receptor EGTA ethyleneglycol-bis-(β-aminoethyl ether)N,N′-tetraacetic acid PMSF phenylmethylsulfonyl fluoride |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|