Functional analysis of ctenophore Shaker K channels: N-type inactivation in the animal roots.

Here we explore the evolutionary origins of fast N-type ball-and-chain inactivation in Shaker (Kv1) K channels by functionally characterizing Shaker channels from the ctenophore (comb jelly) Mnemiopsis leidyi. Ctenophores are the sister lineage to other animals and Mnemiopsis has >40 Shaker-like K channels, but they have not been functionally characterized. We identified three Mnemiopsis channels (MlShak3-5) with N-type inactivation ball-like sequences at their N termini and functionally expressed them in Xenopus oocytes.