Fig. 1.

Comparison of data from Ca²⁺-free and Ca²⁺-treated filaments. (A and B) Data from Ca²⁺-treated filaments, (C and D) data from Ca²⁺-free filaments. (A and C) The five columns represent different viewing angles of the filaments described by the Euler angles α = 0°, β = 90° throughout and then with the angles γ shown below each figure. Rows Ai and Ci are class averages, Aii and Cii are reprojections and Aiii and Ciii are surface views of the 3D reconstruction displayed at the corresponding angles. The cross-correlation coefficient between the class averages and the corresponding reprojections are given at the top of each column for the Ca²⁺-treated state (A) and the corresponding cross-correlations between the inverted class average and the reprojection are shown underneath in brackets. Similar cross-correlations are shown in C for the Ca²⁺-free state (C). (B and D) The surface rendered 3D maps of the Ca²⁺-treated filament (B) and the Ca²⁺-free filament (D). Two viewing angles of the reconstructions are shown with a 90° rotation about the filament axis between the two.