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Block of Shaker B K + channels by Pi1, a novel class of scorpion toxin
Author(s) -
Gómez-Lagunas F,
Olamendi-Portugal T,
Possani L.D
Publication year - 1997
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01387-7
Subject(s) - scorpion toxin , shaker , scorpion , block (permutation group theory) , chemistry , crystallography , toxin , stereochemistry , physics , biochemistry , venom , combinatorics , mathematics , quantum mechanics , vibration
Here we describe the basic features of the interaction of K + channels with Pi1, a recently described 35 amino acid scorpion toxin, which has four disulfide bridges instead of the three commonly found in all the other known scorpion toxins. We found that: (a) Pi1 blocks Shaker B from the outside with a 1:1 stoichiometry, and a K d of 32 nM in zero external [K + ]; (b) extracellular K + , Rb + and Cs + but not NH + 4 ions strongly impede (destabilize) the block by this toxin; interestingly (c) the destabilizing binding of K + , Rb + , and Cs + is described by a Hill coefficient n >1; (d) external K + is more effective than internal K + to reduce the block by Pi1.