κ-Bungarotoxin was first reported in 1983 as a component of the venom of Bungarus multicinctus that differed in biological effect from the previously known
α-bungarotoxin: κ-bungarotoxin, but not α-bungarotoxin, was capable of impeding
nicotinic signaling in the
chickciliary ganglion.[4] Bungarotoxin toxin was designated "kappa" as an
allusion to the Latin word kiliaris ("from the eye"), and to the root of "ciliary".[4] Separately identified toxins designated "toxin F" and "bungarotoxin 3.1" were identified by
protein sequencing as identical to κ-bungarotoxin.[2]
κ-Bungarotoxin is a receptor
antagonist, meaning it blocks the normal response of the receptor to
acetylcholine, which inhibits
neurotransmission and therefore causes
neuromuscularparalysis. Like the
α-bungarotoxins, κ-bungarotoxin causes a
post-synaptic blockade of signaling; this is in contrast to the
β-bungarotoxins which induce a pre-synaptic block.[3] The distinction between the effects of α-bungarotoxin and κ-bungarotoxin was first identified functionally, as differences in effects on specific neural structures.[4][6] The basis of this functional difference has been molecularly characterized as differences in receptor subtype specificity; the pentameric receptors are assembled from different distributions of subunits in
neurons and in
muscles.[5]
Structure
The κ-bungarotoxin polypeptide is 66
amino acids long and folds into an antiparallel
beta sheet structure stabilized by five conserved
disulfide bonds, a structural feature shared by many peptide toxins. Unlike other members of the bungarotoxin family, κ-bungarotoxin is a
dimer.[1]
References
^
abDewan JC, Grant GA, Sacchettini JC (November 1994). "Crystal structure of kappa-bungarotoxin at 2.3-A resolution". Biochemistry. 33 (44): 13147–54.
doi:
10.1021/bi00248a026.
PMID7947721.
^
abLoring RH, Andrews D, Lane W, Zigmond RE (October 1986). "Amino acid sequence of toxin F, a snake venom toxin that blocks neuronal nicotinic receptors". Brain Research. 385 (1): 30–7.
doi:
10.1016/0006-8993(86)91543-x.
PMID3021284.
S2CID41801981.
^
abChiappinelli VA, Weaver WR, McLane KE, Conti-Fine BM, Fiordalisi JJ, Grant GA (1996). "Binding of native kappa-neurotoxins and site-directed mutants to nicotinic acetylcholine receptors". Toxicon. 34 (11–12): 1243–56.
doi:
10.1016/s0041-0101(96)00110-9.
PMID9027980.
^Dryer SE, Chiappinelli VA (December 1983). "Kappa-bungarotoxin: an intracellular study demonstrating blockade of neuronal nicotinic receptors by a snake neurotoxin". Brain Research. 289 (1–2): 317–21.
doi:
10.1016/0006-8993(83)90033-1.
PMID6318897.
S2CID38572091.