Figure 5.

Ca²⁺ permeability and Gd³⁺ block are preserved in TRPV6 constructs with distinct domain arrangements. (a,b) Representative ratiometric fluorescence measurements for HEK cells expressing TRPV6*. Arrows indicate the time at which the corresponding ion was added. After resuspending the cells in nominally calcium-free buffer, addition of Ca²⁺ resulted in robust concentration-dependent increase in Fura-2 signal (a). In contrast, pre-incubation of cells with increasing concentrations of Gd³⁺ resulted in concentration-dependent reduction in Fura-2 signal (b). (c,d) Normalized changes in F₃₄₀/F₃₈₀ at varying concentrations of Ca²⁺ (c) and Gd³⁺ (d) calculated for wild type TRPV6 (blue), TRPV6_cryst (red) and TRPV6* (green). In (d), ΔF₃₄₀/F₃₈₀ was measured after preincubation with Gd³⁺ and subsequent addition of 2 mM Ca²⁺.