β-Bungarotoxin, a Phospholipase That Stimulates Transmitter Release
This extract was created in the absence of an abstract.
Excerpt
Although electrophysiological measurements have provided a detailed, quantitative description of the release of neurotransmitter from nerve terminals, the molecular basis of the release process is unknown. Some information on the mechanism of neurotransmitter release has been obtained by perturbing that process with compounds of known biochemical function, such as cardiac glycosides or mitochondrial uncouples (Birks and Cohen 1968; Glagoleva et al. 1970). Another class of agents that disrupt transmitter release is the presynaptic neurotoxins, which thus provide a potential tool for further elucidation of the molecular mechanisms involved. In the present work, we have studied the biochemical properties of β-bungarotoxin, a presynaptic neurotoxin from the venom of the snake Bungarus multicinctus, as well as the physiological changes it produces in neuromuscular transmission. The data show that β-bungarotoxin is a calcium-dependent phospholipase, A2, which, in the presence of extracellular calcium, causes an initial enhancement of spontaneous, evoked and delayed release before...
