Purity ~90% (HPLC). Gap junctions contain channels that allow the passage of ions and small molecules between adjacent cells. This intercellular communication has been implicated in the coordination of cellular responses to intracellular signaling molecules. Connexins are a family of integral membrane proteins that oligomerize to form intercellular channels that are clustered at gap junctions. Connexins share a common transmembrane (TM) topology. Each connexin is thought to contain 4 TM domains, with two extracellular and three cytoplasmic regions. Connexin-mimetic peptides, i.e. peptides that are identical with a short aa sequence on the Cx subunit have recently emerged as tools to block Connexin hemi-channels (CxHcs) with little or no immediate effects on gap junctions. 40Cx-Gap27 corresponds to aa sequence on the second extracellular loop of Cx40. The sequence comprises conserved domain SRPTEK which interfaces with the membrane. 40Cx-Gap27 inhibits Cx40 gap junctions. Effects of thi