1lir: Difference between revisions

[[Image:1lir.gif|left|200px]]<br /><applet load="1lir" size="350" color="white" frame="true" align="right" spinBox="true"  

Lq2 is a unique scorpion toxin. Acting from the extracellular side, Lq2 blocks the ion conduction pore in not only the voltage- and Ca2+ -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 alpha-helix (residues S10 to L20) and a beta-sheet, connected by an alphabeta3 loop (residues N22 to N24). The beta-sheet has two well-defined anti-parallel strands (residues G26 to M29 and residues K32 to C35), which are connected by a type I' beta-turn centered between residues N30 and K31. The N-terminal segment (residues Z1 to T8) appears to form a quasi-third strand of the beta-sheet.

1LIR is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Leiurus_quinquestriatus_hebraeus Leiurus quinquestriatus hebraeus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LIR OCA].  

[[Category: Lewis, J H.]]

[[Category: Renisio, J G.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 13:45:22 2008''