Figure 3.

Correlation functions for CaM-AF488-TR. (A) CaM in high-Ca²⁺ buffer. G_GG(τ) (black squares), G_RR(τ) (red circles), G_GR(τ) (green triangles), and G_RG(τ) (blue inverted triangles). The solid lines show a global fit with a time constant for intramolecular dynamics of 92 μs plus a static FRET state. (B) CaM in low-Ca²⁺ buffer. The global fit in this case incorporates two static FRET states but no intramolecular dynamics. Fitting parameters are given in Table 2. (C) Normalized correlations (with triplet dynamics removed) for CaM-AF488-TR in high-Ca²⁺ buffer. G_GG(τ), G_RR(τ), G_GR(τ), and G_RG(τ) are shown as black, red, green, and blue lines, respectively. The arrow points to the shift between the auto-correlation and cross-correlation curves showing the presence of intramolecular dynamics. (D) Normalized correlations (with triplet dynamics removed) for CaM-AF488-TR in low-Ca²⁺ buffer. The close overlap between autocorrelation and cross-correlation decays shows that no intramolecular dynamics are detected for apoCaM.