Gap junction 1. Structure of Gap Junction Connexins are four-pass transmembrane proteins, Extracellular six of which assemble to form a channel. a connexon 12 20 different isoforms of connexins in humans and mice /tc c Intracellular Interacting plasma membranes channel 1.5 nm in diameter homomeric gap of 2-4nm connexon two connexons in composed of register forming six subunits heteromeric homotypic heterotypic open channel between adjacent cells connexins connexons intercellular channels1. Structure of Gap Junction ⚫ Connexins are four-pass transmembrane proteins, six of which assemble to form a channel, a connexon. ⚫ ~ 20 different isoforms of connexins in humans and mice Gap junction