Figure 3.

Self-rotation function (κ = 180° section) calculated using POLARRFN in CCP4 (Winn et al., 2011 ▶) in the resolution range 20–3.0 Å with an integration radius of 20 Å; the contour starts at 30% with an interval of 5%. The ω angle varies in the radial direction and the ϕ angle varies along the circumference. Two peaks (marked by arrows) at ω = 18.5°, ϕ = 180° and ω = 71.4°, ϕ = 0°, each with 71% of the magnitude of the origin peak, represent twofold noncrystallographic symmetry (NCS) axes.