Fig. 1

Model of a connexin and gap junction channel. a The connexin monomer. NT, N-terminus; CL, cytoplasmic loop; CT, C-terminus; EL1 and EL2, extracellular loops 1 and 2; M1–M4, transmembrane domains 1–4. b Possible arrangements of connexins in a gap junction channel. The figure shows different components of gap junction channels. Homomeric connexons are formed by a single connexin type. Heteromeric connexons are composed of more than one connexin type. When connexons of the same composition form a gap junction channel, it is classified as a homotypic channel. If the connexons differ in components, the channel is classified as heterotypic