FIGURE 2.

Contributions of aromatic residues in the DIII-IV linker to CaM binding. A–F, ITC traces for titration of calmodulin into the indicated wild type and mutant DIII-IV linker peptides. The thermodynamic properties of the interactions are shown in Table 1 except for Y1494A, which could not be accurately fit. Titrations with this mutant were repeated three times with different preparations of protein, and in each case the results yielded similar thermodynamic properties and binding characteristics. Mutation of the neighboring aromatic, Y1495A, produces a 3-fold loss in binding affinity and 2-fold loss in ΔH (Table 1) confirming a role for this site as well in CaM binding.