PANX1, also named as MRS1, belongs to the pannexin family. It plays a role as a Ca2+-leak channel to regulate ER Ca2+ homeostasis. It is a structural component of the gap junctions and the hemichannels. PANX1 induced the formation of intercellular channels with characteristics of gap junctions. The PANX1 and pannexin 2 are abundantly expressed in central nerve system (CNS) and are coexpressed in various neuronal populations. Studies in Xenopus oocytes suggest that this protein alone and in combination with pannexin 2 may form cell type-specific gap junctions with distinct properties.