Maurotoxin, a four disulfide bridge toxin from Scorpio maurus venom: purification, structure and action on potassium channels.
FEBS Lett
; 406(3): 284-90, 1997 Apr 14.
Article
em En
| MEDLINE
| ID: mdl-9136903
ABSTRACT
A new toxin acting on K+ channels, maurotoxin (MTX), has been purified to homogeneity from the venom of the chactoid scorpion Scorpio maurus. MTX is a basic single chain 34 amino acid residue polypeptide, amidated at its C terminal, and crosslinked by four disulfide bridges. It shows 29-68% sequence identity with other K+ channel toxins, and presents an original disulfide pattern, the last two half-cystine residues (31-34) being connected. Although the first three disulfide bonds have not been defined experimentally, modelling based on the structure of charybdotoxin favored two combinations out of six, one of which has two bridges (3-24 and 9-29) in common with the general motif of scorpion toxins. The last bridge would connect residues 13 and 19. MTX inhibits the binding to rat brain synaptosomal membranes of both [125I]apamin, a SK(Ca) channel blocker (IC50 5 nM), and [125I]kaliotoxin, a Kv channel blocker (IC50 30 pM). MTX blocks the Kv1.1, Kv1.2 and Kv1.3 currents expressed in Xenopus oocytes with IC50 of 45, 0.8 and 180 nM, respectively. MTX represents a member of a new class of short toxins with 4 disulfide bridges, active on voltage-dependent K+ channel and also competing with apamin for binding to its receptor.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Venenos de Escorpião
/
Canais de Potássio
/
Neurotoxinas
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
FEBS Lett
Ano de publicação:
1997
Tipo de documento:
Article
País de afiliação:
Tunísia