Different modes of Ca ²⁺ permeation in TRPV6 and TRPV1. (A) Bottom: The evolution of the z coordinates of permeating Ca²⁺ in TRPV6. Different permeating Ca²⁺ are shown in different colors. Shaded areas indicate the simultaneous 3-Ca²⁺ occupancy in the SF region. Dashed lines denote the boundaries of the narrow pore region. Top: The representative snapshot of Ca²⁺ permeating the SF region. Residues forming the SF are shown as licorice. The Ca²⁺ is shown as a pink sphere. The backbone of protein is shown as a transparent cartoon. Only two chains are shown for clarity. (B) Similar to A, but for TRPV1.