Mapping the site of block by tetrodotoxin and saxitoxin of sodium channel II.
FEBS Lett
; 293(1-2): 93-6, 1991 Nov 18.
Article
em En
| MEDLINE
| ID: mdl-1660007
ABSTRACT
The SS2 and adjacent regions of the 4 internal repeats of sodium channel II were subjected to single mutations involving, mainly, charged amino acid residues. These sodium channel mutants, expressed in Xenopus oocytes by microinjection of cDNA-derived mRNAs, were tested for sensitivity to tetrodotoxin and saxitoxin and for single-channel conductance. The results obtained show that mutations involving 2 clusters of predominantly negatively charged residues, located at equivalent positions in the SS2 segment of the 4 repeats, strongly reduce toxin sensitivity, whereas mutations of adjacent residues exert much smaller or no effects. This suggests that the 2 clusters of residues, probably forming ring structures, take part in the extracellular mouth and/or the pore wall of the sodium channel. This view is further supported by our finding that all mutations reducing net negative charge in these amino acid clusters cause a marked decrease in single-channel conductance.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Saxitoxina
/
Tetrodotoxina
/
Mapeamento de Peptídeos
/
Canais de Sódio
Limite:
Animals
Idioma:
En
Ano de publicação:
1991
Tipo de documento:
Article