Connexins (Cxs) are the major components of gap junctions, aqueous pores that connect the cytoplasms of two adjacent cells and allow the transfer of ions and small molecules less than 1 kDa between them. Connexins structure includes four trans-membrane domains M1–M4, two extracellular domains E1–E2 and three cytoplasmic domains. The cytoplasmic domains include cytoplasmic loop and carboxy-terminus which are characteristic of each connexin. The membrane spanning and the extracellular domain are highly conserved^1,2.

Six connexins proteins forms a connexon, also called hemichannel, which can traffic to the plasma membrane and dock with a hemichannel from an adjacent cell to form an intercellular channel.  Paracrine signaling and the propagation of Ca²⁺ waves are two examples of hemichannels functional roles at the plasma membrane. To date, 19 connexin genes have been found in the mouse genome and 20 in the human genome^1,3.

Connexin 31 (CX31) is highly expressed in the stratum granulosum in the upper differentiating layer of the epidermis. Expression is also detected in peripheral nerves and the cochlea, testis of adults, in placenta, and in developing hindbrain^4,5.

Mutations in Connexin 31 are associated with multiple human diseases including the genetic skin disorder erythrokeratodermia variabilis, hearing impairment and peripheral neuropathy⁴.