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Solution structure of potassium channel‐inhibiting scorpion toxin Lq2
Author(s) -
Renisio JeanGuillaume,
Lu Zhe,
Blanc Eric,
Jin Weili,
Lewis John H.,
Bornet Olivier,
Darbon Hervé
Publication year - 1999
Publication title -
proteins: structure, function, and bioinformatics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.699
H-Index - 191
eISSN - 1097-0134
pISSN - 0887-3585
DOI - 10.1002/(sici)1097-0134(19990301)34:4<417::aid-prot1>3.0.co;2-r
Subject(s) - scorpion , potassium channel , potassium channel blocker , toxin , scorpion toxin , potassium , chemistry , pharmacology , venom , biophysics , biology , biochemistry , organic chemistry
Lq2 is a unique scorpion toxin. Acting from the extracellular side, Lq2 blocks the ion conduction pore in not only the voltage‐ and Ca 2+ ‐activated channels, but also the inward‐rectifier K + channels. This finding argues that the three‐dimensional structures of the pores in these K + channels are similar. However, the amino acid sequences that form the external part of the pore are minimally conserved among the various classes of K + channels. Because Lq2 can bind to all the three classes of K + channels, we can use Lq2 as a structural probe to examine how the non‐conserved pore‐forming sequences are arranged in space to form similar pore structures. In the present study, we determined the three‐dimensional structure of Lq2 using nuclear magnetic resonance (NMR) techniques. Lq2 consists of an α‐helix (residues S10 to L20) and a β‐sheet, connected by an αβ3 loop (residues N22 to N24). The β‐sheet has two well‐defined anti‐parallel strands (residues G26 to M29 and residues K32 to C35), which are connected by a type I' β‐turn centered between residues N30 and K31. The N‐terminal segment (residues Z1 to T8) appears to form a quasi‐third strand of the β‐sheet. Proteins 1999;34:417–426. © 1999 Wiley‐Liss, Inc.