Table 2.

Affinity of WT and V91G D-CaM for the CaM binding region of Drosophila RyR (D-RyR-peptide)

Peptide [Ca2+]	Conditions	Method	Kd (nM) WT	Kd (nM) V91G
D-RyR-Peptide + high	100 mM KCl	Displacement	~73	~125
Ca2+	1 mM CaCl2
D-RyR-Peptide + high	100 mM KCl	Competition	85 (13)	132 (18)
Ca2+	1 mM CaCl2
D-RyR-Peptide + low	100 mM KCl	Competition	Not measurable	Not measurable
Ca2+ (<1 nM)	1 mM EGTA
D-RyR-Peptide + low	0 mM KCl	Competition	470 (60)	1250 (175)
Ca2+ (<1 nM)	1 mM EGTA

Affinities were determined by fluorescence titration methods as detailed in Materials and Methods.