Fig. 2

Crystal structure of the “Ca²⁺ clasp” of BEST1 from Gallus gallus [9, 10]. The calcium binding site is formed by two bestrophin-1 subunits represented by the red (subunit A) and blue ribbons (subunit B) and is involved in the CaCC activation. Ca²⁺ is shown as a dark blue sphere. Yellow lines indicate calcium ion coordination by residues side chains and backbone carbonyl groups of both subunits. A water molecule coordinating the calcium ion in the crystal structure is not shown