Calcium-activated chloride channels (CaCCs) are ubiquitously expressed and implicated in physiological processes such as sensory transduction, fertilization, epithelial secretion, and smooth muscle contraction. The anoctamin family of transmembrane proteins (ANO, TMEM16) belong to CaCCs and have been shown to transport Cl- ions when activated by intracellular Ca2+ (Galietta 2009, Huang et al. 2012). There are currently 10 members, ANO1-10, all having a similar structure, with eight putative transmembrane domains and cytosolic amino- and carboxy-termini. ANO1 and 2 possess Ca2+ activated Cl- transport activity (Yang et al. 2008, Scudieri et al. 2012) while the remaining members also show some demonstrable activity (Tian et al. 2012).
intracellular calcium activated chloride channel activity of ANOs [plasma membrane]
All CLCAs contain a consensus cleavage motif which is recognised by an internal zincin metalloprotease domain within the N terminus. Self-proteolysis within the secretory pathway yields N- and C-terminal fragments, a step critical for CLCA activation of calcium-activated chloride channels (CaCCs) mediated through the N-terminal fragment (Yurtsever et al. 2012).