Figure 9.

Relative decrease of peak height in HNCO NMR spectra of 70 μm MAP2c upon the addition of 70 μm SR4-SR5-SH3 plectin fragment. Secondary structure motifs determined by the ASTEROIDS analysis, hydropathicity, and charge distribution are shown above the plot. The symbols used to describe the secondary structure motifs are explained in the legend to Fig. 4. The hydrophaticity index according to Kyte and Doolittle (85) is shown as darkness of the top bar above the plot (white and black correspond to values of −4.5 and +4.5, respectively). The charge distribution is represented by the color in the bottom bar above the plot, corresponding to a relative electrostatic potential approximated by Σ_jCQ_i/(d₀ + d₁|n_i − n_j|), where Q_i and n_i are charge and sequential number of the ith residue, C is a constant including the electric permitivity, and d_k are distance constants. The ratio d₁/d₀ was set to 2.0, and the colors were chosen so that red and blue correspond to the highest negative and positive potential, respectively, which makes the color code independent of C/d₀ (13). Letters P above the plot indicate positions of prolines.