FIG 5. Binding of Ca²⁺-saturated CaM to reporters containing mutant neuromodulin IQ domains altered to match the PEP19 sequence at positions -1, 3 and 6.

Data for the following reporter constructs are presented: B_IQK⁻¹A (■), B_IQA³Q (●), B_IQG⁶K (▲), and B_IQTr (◆), which contains all three amino acid changes. The complete amino acid sequences of the IQ domains in these reporters are listed in Fig. 1. Apparent K_d values derived from fits of a hyperbolic binding equation to these (solid lines) and similar data are listed in Table 1. Ca²⁺ saturation was effected by addition of ~250 µM free Ca²⁺. Additional experimental details are given in “Experimental Procedures” or in the caption to Fig. 2. Fitted curves for binding of Ca²⁺-saturated CaM to B_IQ (-.-) and B_IQPEP (…) are presented for comparative purposes (see Fig. 2).