Fig. 1

X-ray structure of bestrophin-1 from Gallus gallus [9, 10] forming a calcium-activated chloride transmembrane channel (CaCC) composed of five identical subunits and containing a single long pore along the axis of symmetry. a Top view (extracellular side), b side view, c bottom view (cytosol side, channel aperture). The CaCC is shown in Corey–Pauling–Koltun (CPK) representation, dark green spheres—chloride ions (A), orange spheres—potassium ions (not visible), blue spheres—calcium ions (not visible)