Figure 7

Different kinetics of ratiometric curves for TRPV6* or TRPV6_cryst at physiological extracellular calcium concentration. (a-b), Representative ratiometric fluorescence measurements for HEK cells expressing TRPV6* (a) or TRPV6_cryst (b). Arrows indicate the time at which 2 mM Ca²⁺ was added. The curves were fitted with one (red) or two (blue) exponentials. Note, TRPV6* kinetics was well described by the double but not the single exponential. Over three measurements, the time constants of the single exponential fit (τ_single) were 14.5 ± 2.7 s for TRPV6* and 110 ± 16 s for TRPV6_cryst, τ_fast = 2.2 ± 1.0 s, τ_slow = 54 ± 11 s and A_fast = 0.57 ± 0.01 for TRPV6* and τ_fast = 5.4 ± 2.8 s, τ_slow = 135 ± 23 s and A_fast = 0.10 ± 0.03 for TRPV6_cryst. At n = 3, the values of τ_single and A_fast for TRPV6* and TRPV6_cryst were statistically different (t-test, P < 0.05).