Innexin-3 forms connexin-like intercellular channels

Innexins comprise a large family of genes that are believed to encode inver tebrate gap junction channel-forming proteins. However, only two Drosophila innexins have been directly tested for the ability to form intercellular c hannels and only one of those was active. Here we tested the ability of Cae norhabditis elegans family members INX-3 and EAT-5 to form intercellular ch annels between paired Xenopus oocytes. We show that expression of INX-3 but not EAT-5, induces electrical coupling between the oocyte pairs. In additi on, analysis of INX-3 voltage and pH gating reveals a striking degree of co nservation in the functional properties of connexin and innnexin channels, These data strongly support the idea that innexin genes encode intercellula r channels.