Structural component of the gap junctions and the hemichannels. May play a role as a Ca(2+)-leak channel to regulate ER Ca(2+) homeostasis (By similarity). Structural component of the gap junctions and the hemichannels involved in the ATP release and nucleotide permeation. May play a role as a Ca(2+)-leak channel to regulate ER Ca(2+) homeostasis. Plays a critical role in oogenesis. Homohexamer. Forms homomeric or PANX1/PANX2-heteromeric intercellular channels on coexpression in paired Xenopus oocytes. Widely expressed, including in cartilage, skin, spleen and brain. S-nitrosylation inhibits channel currents and ATP release. N-glycosylation may play a role in cell surface targeting (PubMed:17925379). Exists in three glycosylation states: non-glycosylated (GLY0), high-mannose glycosylated (GLY1), and fully mature glycosylated (GLY2) (By similarity). Belongs to the pannexin family.