Table 1.

Rates of dissociation of Ca²⁺ from Ca²⁺-CaM in the absence or presence of CKIIp

	Free Ca2+-CaM						Ca2+-CaM + CKIIp
	Rate 1	Amp 1	Rate 2			Amp 2	Rate 1	Amp 1	Rate 2		Amp 2
Quin-2	>1000	2		8.9 ± 0.1	2		6.3 ± 1	2.1	0.27 ± 0.04	2
Tyrosine	–	–		9.2 ± 0.2	1		5.5 ± 0.1	0.17	0.25 ± 0.01	0.83
CaM(C75D)	>1000	0.86		5.2 ± 0.2	0.14		5.9 ± 0.1	0.79	0.34 ± 0.01	0.21
FRET							5.8 ± 0.8	0.37	0.23 ± 0.02	0.63

All rates are the average ±SD of four to nine independent experiments.

The amplitudes for data collected using Quin-2 indicate number of moles Ca²⁺ released/mol protein and were obtained by calibrating the response of Quin-2 with Ca²⁺ standards. The moles Ca²⁺ released/mol protein for the fast phase of free CaM could not be accurately fit since about 75% of the signal occurs during the dead time of the instrument. The value of 2 was assigned since CaM binds 4 mol Ca²⁺, and 2 mol Ca²⁺/mol protein were released during the slow phase.

The average amplitudes are given. Amplitudes for Tyr, CaM(C75)D, and FRET indicate the relative fractional amplitude of each phase with 1.0 defined as the total change in fluorescence. Absolute values are used to determine amplitudes for FRET.

– indicates that the best fit was a single exponential.