Hydrophobic interaction selective filters

FIGURE 9.3 One of the first pictures of a tetrameric K" " channel with a selectivity filter made of pore loops. A linear representation of a Shaker K" channel subunit on top shows shaded hydrophobic segments SI—S6 and a region designated the pore loop. A partial amino acid sequence from the Shaker K" channel pore loop highlights amino acids shown to interact with extracellular scorpion toxins ( ), intracellular tetraethylammonium (f), and ions (+). The pore loop was proposed to reach into the membrane (middle) and form a selectivity filter at the centre of four subunits (bottom). (From MacKinnon, 2004. Reproduced with permission from John Wiley Sons.)... 

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