Figure 2. The cadherin-mediated adhesion module.

a) The Cad/Cat complexes form adherens junctions through a multi-step process. The adhesion is initiated by forming cadherin dimers from apposed cell surfaces through the trans-interactions. The clustering of cadherins through the cis-interactions triggers the final formation of adherens junctions. b) The process of junction formation is simplified by using state transition of Cad/Cat complexes. A “free” Cad/Cat complex can transit to “trans” state. Likewise, a “trans” Cad/Cat complex can either participate into clusters by transiting to “cis” state, or breaks down into “free” state. The endocytosis, association and dissociation of Cad/Cat complexes under different adhesive circumstance are also considered in our model.