Fig. 7.

ATP/ADP ratio-dependency of tau protein phosphorylation as probed by electrophoretic mobility. The mixture of tau protein and C-PKA, prepared as described in Materials and Method (Tau-C-PKA) was diluted 1/11.5 in a buffer composed of 15 μl of 10 mM Hepes and 0.1 M NaCl at pH 7, and 10 μl of phosphate buffer containing 250 mM phosphate and 0.1 mg/ml Ampicillin at pH 7. This reaction mixture contained 15 mM MgCl₂, 0.25 mM EGTA, 0.25 mM 2-mercaptoethanol, ATP 0.1 mM and the following ADP concentrations (mM): 0 (lane 2), 0.01 (lane 3), 0.08 (lane 4), 0.25 (lane 5), 0.5 (lane 6), and 1 (lane 7). Lane 1 is a control in the absence of nucleotides. All samples were incubated at 20°C for 22 h. Scanning results are included in Table 1. The rolling ball radius used for subtraction of background was of 11 pixels.