Binding of the sea anemone polypeptide BDS II to the voltage-gated sodium channel

L. E. Llewellyn, R. S. Norton

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Abstract

BDS II, a 43 - residue polypeptide from the sea anemone Anemonia sulcata, is reported to have both antihypertensive and antiviral activity. This polypeptide possesses a number of sequence and structural similarities to a class of cardiotonic proteins which bind to receptor site 3 of the voltage-gated sodium channel. In contrast to these cardiostimulant proteins, which produce positive inotropic effects at concentrations of 2-15nM, BDS II produced a weak negative inotropic effect upon isolated guinea-pig atria, with doses of 90 and 180nM depressing contractile strength by 15 and 28%, respectively. BDS II also competed with a 125-iodine labelled derivative of AP-A (a representative of the cardiostimulant proteins) bound to sodium channels in rat brain synaptosomes. The IC50 for BDS II versus AP-A was 5.2μM. BDS II may therefore be considered an antagonist for receptor site 3 of the voltage-gated sodium channel. Structural differences between BDS II and the agonist AP-A which may give rise to their different effects on the sodium channel are considered.

Original languageEnglish
Pages (from-to)937-946
Number of pages10
JournalBiochemistry International
Volume24
Issue number5
Publication statusPublished - 1991
Externally publishedYes

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