FIGURE 1.
N-terminal portion of TnC, showing engineered FRET donor Trp-12 (D) and FRET acceptor Cys-51-labeled AEDANS (A). (a) Ca2+-bound TnC in the absence of TnI (modified from PDB ID code 1AP4). (b) The Ca2+-bound TnC with bound TnI-R (brown helix) (modified from PDB ID code 1J1E). The efficiency of photon transfer between the emission dipole of Trp-12 and the absorption dipole of AEDANS (shown) depends on the interprobe distance (R), which changes upon hingelike movement of helix B of TnC (αB) during activation.