Figure 5.

Solution structure of CaM in complex with CaNp. (A) The ensemble of 20 best structures of the complex of CaM and CaNp is superimposed. The backbone structures of the N-domain, C-domain, and tether region of CaM are colored coded in blue, red, and grey respectively. Ca²⁺ ions are shown as grey spheres. The CaNp is colored coded in green. The N- and C-termini of CaM and CaNp are labeled as N and C respectively; (B) The ribbon representation of CaM/CaNp complex structure. The complex structure shows an ellipsoidal shape with 8 α-helices (α₁–α₈) of CaM wrapping the CaNp helix; (C) Side view of the ribbon representation of CaM/CaNp complex structure. CaNp shows a curved helical conformation centered at the residue Gly⁴⁰⁴; (D) The structural changes of the two domains of CaM upon binding to CaNp. The structure of free CaM (in yellow) superimposed with the structure of CaM when associated with CaNp. The N-domain and C-domain of CaM in the bound form is colored in blue and red respectively. N-domain of CaM, especially helix I (α₁) undergoes larger structural changes upon association with CaNp, whereas C-domain of CaM remains unchanged.