Kraus Johanna E. M.

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Kraus
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Johanna E. M.
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  • Article
    Convergent evolution of sodium ion selectivity in metazoan neuronal signaling
    (Cell Press, 2012-08-30) Barzilai, Maya Gur ; Reitzel, Adam M. ; Kraus, Johanna E. M. ; Gordon, Dalia ; Technau, Ulrich ; Gurevitz, Michael ; Moran, Yehu
    Ion selectivity of metazoan voltage-gated Na+ channels is critical for neuronal signaling and has long been attributed to a ring of four conserved amino acids that constitute the ion selectivity filter (SF) at the channel pore. Yet, in addition to channels with a preference for Ca2+ ions, the expression and characterization of Na+ channel homologs from the sea anemone Nematostella vectensis, a member of the early-branching metazoan phylum Cnidaria, revealed a sodium-selective channel bearing a noncanonical SF. Mutagenesis and physiological assays suggest that pore elements additional to the SF determine the preference for Na+ in this channel. Phylogenetic analysis assigns the Nematostella Na+-selective channel to a channel group unique to Cnidaria, which diverged >540 million years ago from Ca2+-conducting Na+ channel homologs. The identification of Cnidarian Na+-selective ion channels distinct from the channels of bilaterian animals indicates that selectivity for Na+ in neuronal signaling emerged independently in these two animal lineages.