(A) Overlay of 13 different CRM1-bound NESs: mDia2NES, CDC7NES, X11L2NES, FMRPNES, SMAD4NES, HDACNES, PaxNES and FMRP-1bNES, SNUPNNES (3GB8), PKINES(Φ0L) (3NBY), RevNES (3NBZ), hRio2NES (5DHF), CPEB4NES (5DIF) (shown as ribbons with Φ residues in sticks; their CRM1 H12A helices were superimposed). A grey rectangle highlights the only secondary structural element shared by all 13 NESs: a single turn of helix. (B) Ramachandran plot of phi/psi angles of the four residues in each of the conserved one-turn of helix. Arrows indicate changes in psi angles along the polypeptide direction. For example, (+) HDAC5NES: Φ2 Ψ = −43.5°, Φ2+1Ψ = −21.7°, Φ2+2Ψ = −1.3°, Φ3 Ψ = 133.8° and (−) CPEB4NES: Φ2+2Ψ = −40.2°, Φ2+1Ψ = −31.0°, Φ2 Ψ = 16.5°, Φ2-1Ψ = 111.5°. *Residues in SNUPNNES plotted are Φ2+1, Φ2+2, Φ2+3 and Φ3. (C) Detailed view of niche motifs in (+) NESs, FMRPNES and mDia2NES.