FIGURE 7.

Ca²⁺/DA-CaM trapping in phospho-Thr²⁸⁶-αCaMKII during Thr^305/306-autophosphorylation. 0.5 μm DA-CaM and 1 μm αCaMKII were preincubated at 37 °C; DA-CaM fluorescence intensity was defined as 1. At the point indicated by an arrow, 1 mm ATP was added, resulting in substantial quenching of DA-CaM fluorescence, indicating its adopting a compact conformation bound to phospho-Thr²⁸⁶-αCaMKII. As indicated by the second arrow, at 1600 s, 4.2 mm EGTA was added, resulting in unquenching of DA-CaM fluorescence, indicating the stretching of DA-CaM to an extended conformation.