Table 1.

Interactions between Ca²⁺ and amino acids of WT and mutant Ca²⁺ activation sites

			Amino Acid Interactions
Ca2+ Interactions	Class 5TAQ (Closed) Distance, Å	Class 5TAL (Open) Distance, Å	Class 5TAQ (Closed)	Distance, Å	Class 5TAL (Open)	Distance, Å	Type
WT variant
E3893(OE1)	2.4	2.3	H3895(ND1) - Q3970(O)	3.0	H3895(ND1) - Q3970(O)	3.0	Attractive
E3893(OE2)	2.1	2.2	H3895(N) - E3893(O)	3.5	H3895(N) - E3893(O)	3.5	Attractive
E3893(O)	3.8				Q3970(OE1) - E3967(OE1)	3.3	Repulsive
E3967(OE1)	2.5	2.4
E3967(OE2)	2.2	2.3
T5001(O)	2.6	2.5
Q3970E variant
E3893(OE1)	2.4	2.3	H3895(ND1) - E3970(O)	3.0	H3895(ND1) - E3970(O)	3.0	Attractive
E3893(OE2)	2.1	2.2	H3895(N) - E3893(O)	3.5	H3895 (N) - E3893 (O)	3.5	Attractive
E3893(O)	3.8		E3970(OE1) - E3967(OE1)	3.3	E3970(OE1) - E3967(OE1)	3.0	Repulsive
E3967(OE1)	2.5	2.4
E3967(OE2)	2.2	2.3
T5001(O)	2.6	2.5
Q3970K variant
E3893(OE1)	2.4	2.3	K3970(NZ) - T3966(OG1)	3.9	K3970(NZ) - T3966(OG1)	3.8	Attractive
E3893(OE2)	2.1	2.2	K3970(NZ) - E3967(OE2)	2.9	K3970(NZ) - E3967(OE2)	2.6	Attractive
E3893(O)	3.8		K3970(O) - H3895(ND1)	3.0	K3970(O) - H3895(ND1)	3.0	Attractive
E3967(OE1)	2.5	2.4	H3895(N) - E3893(O)	3.5	H3895(N) - E3893(O)	3.5	Attractive
E3967(OE2)	2.2	2.3
T5001(O)	2.6	2.5

Strong electrostatic interactions (distance <3.5Å) are shown in Fig. 5 as blue dashed lines and weak electrostatic interactions (distance >3.5Å) are shown as red dashed lines between Ca²⁺ and type 1 ryanodine receptor (RyR1) residues. Distances less than 3.5Å formed between inter-residues in RyR1-Q3970K are shown as blue dashed lines; repulsive interactions are shown as green dotted lines. WT, wild type.