Heterologous Functional Expression of an Ascidian Nav1 Channel with Close Relationship with Ancestor of Vertebrate Neuronal Nav Channels

Abstract

The voltage-gated sodium channels (Nav1) consist of the main subunit, alpha subunit, and two types of auxiliary subunits (βετα1/3, and βετα2/4). There are ten alpha subunit genes of Nav in mammals whose expressions are regulated by a tissue or cell type specific manner. Basic common properties of Nav1 including gating and ion permeation have been described classically in squid giant axon and other invertebrate preparations before the age of patch clamping. Detailed information of structure-function relationship of Nav1 has recently been obtained by heterologous expression experiments such as those in Xenopus oocytes or cultured mammalian cells, and very recently by cryo-EM structural analyses of mammalian Nav1s.