CX37

Cx37, also known as connexin-37, is a member of the connexin family of gap junction proteins. It is encoded in humans by the GJA4 gene. Gap junctions formed by connexins create direct cytoplasmic connections between neighboring cells, enabling rapid exchange of ions and small signaling molecules to coordinate cellular activities.

Cx37 has the typical connexin architecture: four transmembrane domains, two extracellular loops, and cytoplasmic N- and C-termini. Six connexin subunits assemble into a hexameric connexon; docking of two connexons from adjacent cells forms a gap junction channel. Cx37 channels typically have a selectivity for ions and small metabolites up to around 1 kDa. Cx37 can form homomeric channels composed solely of Cx37 and can also participate in heteromeric channels with other connexins, such as Cx40 or Cx43, which may modify conductance and permeability.

In humans, Cx37 expression is enriched in endothelial cells lining blood vessels and in placental vasculature, with broader expression reported in some tissues. In the endothelium, Cx37-mediated gap junction communication contributes to coordination of vascular functions, including regulation of vascular tone, barrier properties, and angiogenic remodeling. It may also influence leukocyte transmigration and inflammatory responses through intercellular signaling.

Genetic and experimental studies implicate Cx37 in vascular development and homeostasis. Altered expression or function of GJA4 has been studied in the context of vascular disorders and inflammatory conditions, though specific causal relationships require further investigation.