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Β-Bungarotoxin
Chemical compound From Wikipedia, the free encyclopedia
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β-Bungarotoxin is a form of bungarotoxin that is fairly common in Krait (Bungarus multicinctus) venoms. It is the prototypic class of snake β-neurotoxins. There are at least five isoforms, coded β1 to β5, assembled from different combinations of A and Bchains.[1]
The toxin is a heterodimer of two chains. The A chain confers phospholipase A2 (PLP A2) activity, and the B chain, like dendrotoxins, have a Kunitz domain. There are many isoforms of these chains: examples of A chains include A1 (P00617), A3 (P00619), and A4 (P17934), and examples of B chains include B2 (P00989) and B3 (Q75S50). The B chain plays a functional role in inducing apoptosis.[2]
The target of this neurotoxin is at the presynaptic terminal, where it blocks release of acetylcholine. It seems to do so by blocking the phosphorylation of MARCKS.[3] It is thought that the dendrotoxin-like B chain acts first by inhibition of ion channels, causing cessation of twitches followed by a prolonged facilitatory phase. The A chain (bearing phospholipase activity) then induces a blocking phase by destruction of phospholipids.[4]
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Binding sites
Neurobiological research from the late 1980s has found that beta-bungarotoxin selectively binds to (125)I-DTX-I receptor.
See also
References
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