Cx32

Cx32, or connexin 32, is a gap junction protein belonging to the connexin family. It is encoded by the GJB1 gene on the X chromosome and forms intercellular channels that allow the direct transfer of ions and small metabolites between adjacent cells.

Structurally, Cx32 is a transmembrane protein with four membrane-spanning domains, two extracellular loops, and cytoplasmic N- and C- termini. Six Cx32 subunits assemble into a hexameric connexon, and docking of connexons from neighboring cells creates a gap junction channel. The channels permit passage of ions and small molecules up to roughly 1 kDa, enabling electrical coupling and metabolic coordination between connected cells.

Cx32 is most abundantly expressed in the liver, where it participates in hepatocyte coupling and coordinated metabolism, and in Schwann cells of the peripheral nervous system, where it supports myelin maintenance. It is also present at lower levels in other tissues, including the brain and pancreas.

Clinical relevance of Cx32 centers on GJB1 mutations, which cause X-linked Charcot–Marie–Tooth disease type 1X (CMTX1). Affected individuals typically develop distal sensorimotor neuropathy with weakness and sensory loss, often beginning in adolescence or early adulthood. In males, symptoms tend to be more severe; female carriers may have milder or episodic manifestations. Some patients experience transient neurologic symptoms during fever or strenuous exercise. The disease reflects disrupted gap junctional communication in Schwann cells, among other potential effects.

Diagnosis is confirmed by genetic testing for GJB1 variants, supported by nerve conduction studies. There is no cure; management is supportive, including physical and occupational therapy and mobility aids. Research continues into genotype–phenotype relationships and potential therapeutic approaches targeting gap junction function.