An innexin is a member of a family of proteins that create gap junctions in invertebrates. The innexin proteins have four transmembrane spanning units and, like the vertebrate connexin gap junction protein, six innexin subunits together form a channel, an "innexon", in the plasma membrane between the inside and outside of the cell. Two innexons in apposed plasma membranes can form a gap junction. Innexin genes have homologues in vertebrates called pannexins. However, increasing evidence suggests that pannexons do not form gap junctions unless overexpressed in tissue. Thus, pannexins and innexins differ functionally.

An innexin is a member of a family of proteins that create gap junctions in invertebrates. The innexin proteins have four transmembrane spanning units and, like the vertebrate connexin gap junction protein, six innexin subunits together form a channel, an "innexon", in the plasma membrane between the inside and outside of the cell. Two innexons in apposed plasma membranes can form a gap junction. Innexin genes have homologues in vertebrates called pannexins. However, increasing evidence suggests that pannexons do not form gap junctions unless overexpressed in tissue. Thus, pannexins and innexins differ functionally.