Silver as a probe of pore-forming residues in a potassium channel

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Science  14 Apr 1995:
Vol. 268, Issue 5208, pp. 304-307
DOI: 10.1126/science.7716526


In voltage-dependent potassium channels, the molecular determinants of ion selectivity are found in the P (pore) region, a stretch of 21 contiguous residues. Cysteine was introduced at each P region position in a Shaker potassium channel. Residues projecting side chains into the pore were identified by means of channel inhibition by a sulfhydryl-reactive potassium ion analog, silver ion. The pattern of silver ion reactivity contradicts a beta barrel architecture of potassium channel pores.