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.