Figure 3.

Frequency distribution of unbinding forces between tip- and plate-attached PEG/VE-cadherin-Fc measured at retrace velocities of 800 nm·s⁻¹ and various tip-to-plate encounter intervals. Frequency distribution is expressed as probability density function (n = number of unbinding events). (A) Data shown fit to three Gaussian distributions with peak values (μ1–μ3) at about 40, 75, and 120 pN. (B) Dependency of the frequency of μ1–μ3 on encounter duration indicates a diffusion-limited reaction underlying multimerization of tip- and plate-bound cadherins. Synchronous dirsuption of independent bonds is highly unlikely (see Discussion).