Identification by cross-linking of a beta-bungarotoxin binding polypeptide in chick brain membranes.

Abstract

beta‐Bungarotoxin (beta‐BTX) is a snake venom neurotoxin which inhibits neurotransmitter release from different types of nerve terminals. To identify presynaptic membrane components potentially important in neurosecretion, 125I‐labeled beta‐BTX (mol. wt. 21 000) was cross‐linked to a high‐affinity binding site in synaptic membrane fractions of chick brain using the photoactivable cross‐linker N‐succinimidyl‐6(4′‐azido‐2′‐nitrophenylamino)‐hexanoate. Electrophoretic analysis of the cross‐linked membrane proteins under both reducing and non‐reducing conditions revealed a single [125I]beta‐BTX‐polypeptide adduct of apparent mol. wt. 116 000 (+/‐ 2000). The labeling of this band was prevented under conditions previously shown to inhibit the binding of [125I]beta‐BTX to its high‐affinity binding site. It is concluded that the cross‐linking procedure identified a polypeptide of the presynaptic binding site for beta‐BTX, and that this polypeptide has a mol. wt. of 95 000.

Rattlesnake Neurotoxin Structure, Mechanism of Action, Immunology and Molecular Biology

“…(1986) has described such a receptor, but no characterization was done. A similar membrane protein was reported earlier by Rehm and Betz (1983) for B-bungarotoxin. We were interested in searching for such a receptor moiety, and if found determine its make up, molecular weight, association characteristics, etc.…”

Protein complexes in snake venom

“…Chain B binds to the K ? channels in the target presynaptic site due to its high affinity interaction and in turn helps chain A to bind to the presynaptic site [17][18][19].…”

Immunological evidence for a relationship between the dendrotoxin‐binding protein and the mammalian homologue of the Drosophila Shaker K+ channel

“…DMB protein turned out to be a family of pharmacologically and structurally closely related proteins [23] which consist of at least two types of subunits of apparent molecular masses 80 and 38 kDa [22,23]. The 80 kDa subunit binds the toxin, and is glycosylated [19,24,25]; deglycosylation reduces its molecular mass to 65 kDa [25]. Because the voltagedependent K ÷ channels of the genetic and the biochemical approaches had similar molecular masses, we investigated the immunological rela-tionship between DMB protein and the mammalian Shaker K + channel.…”