(A and B) Helicities of the TADs of c-Myb (A) and pKID (B) predicted by AGADIR (22) at 303 K and 288 K, respectively. (C and D) Deviations of 13Cα (red) and 13C′ (blue) chemical shifts from sequence-corrected (19) random coil shifts for intrinsically disordered proteins (20), applied to Myb32 (C, chemical shifts at 303 K) and pKID (D, chemical shifts at 288 K) (9). The predicted population of helix between residues 290 and 301 of Myb32 (66%) is in close agreement with experiment (70%, estimated from 13Cα and 13C′ shifts). For pKID, the population of helix between residues 117 and 129 (spanning helix αA of pKID bound to KIX) (6) estimated from the secondary chemical shifts is 46%. Residues 133–144 (helix αB of bound pKID) have no measurable propensity to adopt regular helical structure in the free pKID.