X dimerization interface is not essential for mutant recruitment into the junctions. (A, left) Central extrajunctional regions of the cells expressing the control mutant EcDendra-Δ748-KL (Δ748) or its X dimer–incompetent variant (K14E) were photoactivated (the activated area is marked on the right; A), and recruitment of the activated proteins into the junction was then followed by live cell imaging. At each time point (indicated in min), cells were imaged in green and red channels. Note that junctions in the case of the K14E mutant exhibit very weak red fluorescence. (A, right) The same experiment but performed with K14E mutant–expressing cells immediately after placing cells in low-calcium media. Note that activated cadherin is not recruited into the junction. Bar, 5 µM. (B) The graph (average of four independent extrajunctional Dendra activation experiments; n = 30) shows red fluorescence in individual junctions over time. The error bars represent SD. (C) The quantification of red/green individual junction fluorescence 10 min after activation of the cellular center. The mean values of eight junctions from three independent experiments are shown (n = 20). The error bars indicate SD.