Purinergic signalling Nucleoside transporters Pannexins (from Greek 'παν' — all, and from Latin 'nexus' — connection) are a family of vertebrate proteins identified by their homology to the invertebrate innexins.
[1] While innexins are responsible for forming gap junctions in invertebrates, the pannexins have been shown to predominantly exist as large transmembrane channels connecting the intracellular and extracellular space, allowing the passage of ions and small molecules between these compartments (such as ATP and sulforhodamine B).
They transport Ca2+, ATP, inositol triphosphate and other small molecules and can form hemichannels with greater ease than connexin subunits.
[5] Hypothetical roles of pannexins in the nervous system include participating in sensory processing, synchronization between hippocampus and cortex, hippocampal plasticity, and propagation of calcium waves.
According to one of the hypotheses, pannexins also may participate in pathological reactions, including the neural damage after ischemia and subsequent cell death.