ANO1

Anoctamin-1 (ANO1) also known as Transmembrane member 16A (TMEM16A) is a protein that, in humans, is encoded by the ANO1 gene. Anoctamin-1 is a voltage-sensitive calcium-activated chloride channel that is expressed in smooth muscle and epithelial cells; it is highly expressed in human interstitial cells of Cajal (ICC) throughout the gastrointestinal tract. Changes in ANO1 channel activity directly/positively correlate with ICC activity.

Function

ANO1 is a transmembrane protein that functions as a calcium-activated chloride channel.Ca²⁺, Sr²⁺, and Ba²⁺ activate the channel.

Structure

No atomic resolution structure of this channel has yet been obtained. However, biochemical evidence suggests that the channel assembles as a dimer of two ANO1 polypeptide subunits. From hydropathy plotting, each subunit is thought to encode a molecule with eight transmembrane domains, with a reentrant loop between the fifth and sixth transmembrane domains. The reentrant loop is thought to be a P loop-like structure responsible for the ion selectivity of the protein.