TABLE 3.

Transitions between ion binding sites

Configuration 1		Na+		K+		Rb+		Cs+
t event (ns)	Initial	0.002	0.3	0.3		0.3		0.02
S0
S1	+
S2		+	+	+		+		+
S3	+
S4		+		+		+		+
Cavity	+	+	2+	+		+		+
Configuration 2		Na+		K+		Rb+		Cs+
t event (ns)	Initial	0.002	1.0	0.23		0.2	0.5	0.125
S0	+
S1		+				+
S2	+		+	+			+	+
S3		+				+
S4	+		+	+			+	+
Cavity		+	+	+		+	+	+
Configuration 3		Na+		K+		Rb+		Cs+
t event (ns)	Initial	0.1	1.25	0.05	1.7	0.2		0.125	1.1	1.35
EC					+					+
S0
S1	+
S2		+	+		+	+	+	+
S3	+								+	+
S4	+	+			+	+	+	+
Cavity		+	2+		+		+	+	2+	+

This table records the location of the M⁺ ions (for each of the three initial configurations) at preferred sites during each simulation. Approximate times at which concerted motion of the ions and water molecules occurred are given. S0–S4 represent the binding sites in the filter (see Fig. 1), and EC is the extracellular mouth of the channel, adjacent to the filter.