Ion channel chameleons: Switching ion selectivity by alternative splicing.

Voltage-gated sodium and calcium channels are distinct, evolutionarily related ion channels that achieve remarkable ion selectivity despite sharing an overall similar structure. Classical studies have shown that ion selectivity is determined by specific binding of ions to the channel pore, enabled by signature amino acid sequences within the selectivity filter (SF). By studying ancestral channels in the pond snail (Lymnaea stagnalis), Guan et al. showed in a recent JBC article that this well-established mechanism can be tuned by alternative splicing, allowing a single Ca _V 3 gene to encode both a Ca ²⁺ -permeable and an Na ⁺ -permeable channel depending on the cellular context. These findings shed light on mechanisms that tune ion selectivity in physiology and on the evolutionary basis of ion selectivity.
Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article.
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