Table 2. Ca²⁺ binding constants for native and mutant CaMs in the presence and absence of BSCaM_IQ.

The nomenclature used here is defined in the legend to Table 1. The “F” superscript identifies dissociation constants derived from data for Ca²⁺-dependent dissociation of mutant CaM-BSCaM_IQ complexes. Otherwise, all dissociation constants were derived from direct Ca²⁺ binding measurements as described under “Materials and Methods.” Standard errors were derived from the diagonal elements in the variance-covariance matrices for fits to at least five pooled data sets. K_1,2 and K_3,4 are the geometric means of the Ca²⁺-binding constants for the C-ter or N-ter EF hand pair.

	μM						μM2
	K1	K2	K3	K4	K1,2	K3,4	K1K2	K3K4
NC	11.2±5.4	0.3±0.2	25.1±10.3	5.0±2.6	1.8±0.1	11.2±1.0	3.1±0.2	126±11.4
NxC	14.1±4.9	0.2±0.1	–	–	1.6±0.2	–	2.4±0.3	–
NCx	–	–	24.0±9.5	3.9±1.6	–	9.7±1.0	–	93.3±9.2
NC-B	10.7±3.8	2.4±0.8	7.8±3	1.6±0.7	5.1±0.7	3.5±0.6	25.7±3.5	12.3±1.9
NxC-B	22.4±11.3	1.1±0.6	–	–	4.9±0.5	–	24.6±2.7	–
NxC-BF	23.2±8.6	0.7±0.2	–	–	4.0±0.3	–	16.1±1.1	–
NCx-BF	–	–	122±68.0	9.4±4.0	–	33.8±4.0	–	1140±122.0