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  • Title: A functional connection between the pores of distantly related ion channels as revealed by mutant K+ channels.
    Author: Heginbotham L, Abramson T, MacKinnon R.
    Journal: Science; 1992 Nov 13; 258(5085):1152-5. PubMed ID: 1279807.
    Abstract:
    The overall sequence similarity between the voltage-activated K+ channels and cyclic nucleotide-gated ion channels from retinal and olfactory neurons suggests that they arose from a common ancestor. On the basis of sequence comparisons, mutations were introduced into the pore of a voltage-activated K+ channel. These mutations confer the essential features of ion conduction in the cyclic nucleotide-gated ion channels; the mutant K+ channels display little selectivity among monovalent cations and are blocked by divalent cations. The property of K+ selectivity is related to the presence of two amino acids that are absent from the pore-forming region of the cyclic nucleotide-gated channels. These data demonstrate that very small differences in the primary structure of an ion channel can account for extreme functional diversity, and they suggest a possible connection between the pore-forming regions of K+, Ca2+, and cyclic nucleotide-gated ion channels.
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