Table S1.

Contour lengths for C1C2 and C1C2^4D force:extension curves

Fragment	LC, nm				∆LC, nm
	Peak number				Peaks
	0	1	2	3	0–1	1–2	2–3
C1C2
Mean		45.28	71.91	104.99		26.63	33.07
SD		6.91	7.75	8.16		5.95	5.04
n		24	24	24		24	24
C1C24D
Mean	17.50	37.94	63.66	92.23	20.67	25.73	28.78
SD	5.16	7.73	10.24	9.15	5.73	8.20	5.35
n	21	21	21	19	19	19	16
C1C2 + Ca2+
Mean		44.56	72.47	103.98		28.03	31.51
SD		7.05	9.01	11.55		7.32	7.58
n		13	14	14		13	14
C1C24D + Ca2+
Mean	17.22	38.47	65.28	96.78	19.27	26.81	31.50
SD	1.07	6.80	8.76	12.44	3.21	5.75	8.14
n	2	17	17	17	2	17	17

Shown is the extended contour length (L_C) at each numbered peak and the change in contour length between numbered peaks associated with the preceding unfolding event (ΔL_C). n, number of molecules.