Table 1.

Material property values of PCDH15

[Ca2+]	b, nm	lclinker, nm	kfolded, mN/m	ΔlcA, nm	ΔlcB, nm	ΔlcC, nm
3 mM	2.9 ± 0.5	1.4 ± 0.5	9 ± 4	4.0 ± 0.2	15.8 ± 0.7	—
20 µM	3.1 ± 0.4	1.3 ± 0.5	11 ± 5	3.9 ± 0.4	15.0 ± 0.6	35 ± 1

The parameters of a polymer model (SI Appendix) were as follows: b, length of each stiff segment of the folded protein; lc_linker, contour length of each flexible linker between the stiff segments; k_folded, enthalpic stiffness of the folded protein; Δlc_A, contour length increase, type A; Δlc_B, contour length increase, type B; Δlc_C, contour length increase, type C. The parameter values were determined from fits of the model to the force-extension curves in Fig. 2. The values for the folded protein are largely independent of the Ca²⁺ concentration. Δlc_C is in good agreement with the expected contour-length change per unfolded cadherin domain. Fitted parameter values are given as mean ± SEM for five experiments at a Ca²⁺ concentration of 3 mM and for eight experiments at a Ca²⁺ concentration of 20 µM.