Figure 5. Potential artefacts arising from the use of the combined chemical shift (CCS) projection and an alternative CHESCA algorithm to account for them.

(A) Selected inter-residue pairwise CCS correlation between two residues, I163 and Q177, with different fractional activations for the Rp-bound state. (B) HSQC cross-peak positions for residue I163. The CCS values of the five states are displayed in the insert. (C) Illustration of the similarity between the use of CCS and the projection of 2D (¹H, ¹⁵N) cross-peaks into a single axis rotated by an angle β (equation 2). Different 2D (H,N) cross-peaks (black filled and red open diamonds) may result in similar CCS values (circles). (D) Scheme for a CHESCA approach designed to circumvent the projection compression effect (“CHESCA-I”). Two independent CHESCA-CL implementations are applied to the nitrogen and proton chemical shifts using a 0.95 |r_ij| cutoff value (H- and N-CHESCAs) and only the residues that are conserved between the two complete-linkage clusters generated by the H- and N-CHESCAs are included in the functional network. (E) Rp-bound fractional activations for PKA RIα (91-244) with residues from the CHESCA-I method shown as blue lines. Solid and dashed horizontal lines are defined as in Figure 2C.