Inx1Inx7

Inx1Inx7 refers to a heteromeric gap junction channel formed by the innexin proteins INX-1 and INX-7. Innexins are the invertebrate counterparts of connexins and pannexins, creating intercellular channels that enable direct electrical and metabolic communication between neighboring cells.

Formation and structure: INX-1 and INX-7 can co-assemble into heteromeric hemichannels that dock with their counterparts on adjacent cells to form functional gap junction channels. Each hemichannel is typically composed of six subunits, and the resulting channel can exhibit conductance and permeability properties distinct from homomeric channels. Innexins generally share a four-transmembrane-domain topology with two extracellular loops, and the specific INX-1/INX-7 combination influences gating and substrate selectivity.

Expression and localization: INX-1 and INX-7 are expressed in particular tissues of invertebrates, notably within nervous system and muscle cells in model organisms such as C. elegans and Drosophila. The INX-1 INX-7 pair localizes to gap junction plaques at sites of cell–cell contact, facilitating intercellular coupling.

Function and significance: The INX-1 INX-7 heteromeric channels mediate rapid electrical synapses and allow passage of ions and small metabolites between connected cells. This coupling supports synchronized neural activity and coordinated muscle function. The heteromeric combination provides regulatory versatility, enabling tissue- and development-dependent modulation of electrical coupling.

Research status: Evidence from heterologous expression systems and in vivo studies supports the existence of INX-1 INX-7 channels and their biophysical and physiological roles. Ongoing work aims to delineate precise expression patterns, channel properties, and organismal impact.

See also: Innexin, Gap junction, C. elegans innexins.