UNC9

unc-9 is a gene in the nematode Caenorhabditis elegans that encodes an innexin, a transmembrane protein that forms gap junction channels in invertebrates. Innexins are responsible for forming intercellular channels that enable direct electrical and chemical communication between adjacent cells.

Innexins assemble into hexameric hemichannels, called innexons, that dock with channels on neighboring cells to create intercellular conduits. UNC-9 shares the characteristic four-transmembrane domain topology, two extracellular loops, and cytoplasmic N- and C- termini typical of innexins.

UNC-9 is expressed in a broad set of neurons and body-wall muscle cells and participates in electrical synapses that help couple neural and muscular activity, contributing to locomotion.

It forms gap junctions with other innexins, notably UNC-7, to create specific electrical connections that influence circuit function and development.

Mutants show uncoordinated movement, reflecting defective electrical coupling. UNC-9 has been a widely used model for studying gap junction biology and nervous-system development; innexins, including UNC-9, are the invertebrate counterparts of vertebrate connexins and pannexins.