 If all three classes of Pcdhs could engage in multimerization of stochastically expressed Pcdhs isoforms, then neurons could produce a large number of distinct homophilic interaction units, amplifying significantly the cell-surface diversity more than the one afforded by stochastic gene expression alone.As for cytoplasmic domain, all the three classes of clustered Pcdhs proteins are dissimilar, although they are strictly conserved in vertebrate evolution, suggesting a conserved cellular function.This is corroborated by a large number of other interacting proteins including phosphatases, kinases, adhesion molecules and synaptic proteins The cytoplasmic domain also mediates intracellular retention, a property which distinguishes the clustered protocadherins from the related classical cadherins.