Figure 2: Label positions and their visualization.
From: Four-colour FRET reveals directionality in the Hsp90 multicomponent machinery
The top row shows the position of the fluorescence labels in the crystal structure (PDB 2CG9) and the bottom row the pictograms used in the following, triangles depict fluorescence. At each configuration, the highest-energy fluorophore is excited. (a) One donor fluorophore (Atto488) in each of the monomers of Hsp90 at position 61. On excitation, both fluorophores will show fluorescence. (b) Same as in a with an additional acceptor (Atto594) in p23 at position 2. The acceptor will show fluorescence on binding. (c) One donor (Atto488) at position 61 in Hsp90 and one acceptor (Atto550) at position 385 in Hsp90. The acceptor will show fluorescence on closing of Hsp90. (d) Same as in c with an additional acceptor (Atto647N) at the γ-phosphate of ATP. The latter will show fluorescence on binding. (e) Same as in d with an additional acceptor (Atto594) at position 189 in p23. The fluorophore on p23 shows fluorescence if all components are together.
