Fig. 1.

Schematic structures and spectral properties of YC3.12 and the new YC variants. (A) The three-dimensional structure of GFP with the positions of the original (Met-1) and new N termini (Thr-49, Gln-157, Asp-173, Leu-195, and Ile-229) are indicated. (B) Domain structures of YC3.12, YC3.20, YC3.30, YC3.60, YC3.70, and YC3.90. XCaM, Xenopus CaM; E104Q, mutation of the conserved bidentate glutamate (E104) at position 12 of the third Ca²⁺ binding loop to glutamine. (C) Emission spectra of YC variants (excitation at 435 nm) at zero (dotted line) and saturated Ca²⁺ (solid line).