Homer with its EVH1 domain binds to proline-rich motif of Shank family members. Shank and Homer coimmunoprecipitate from brain and colocalize at postsynaptic densities. Shank uses distinct domains to bind to GKAP and Homer, thus it can bridge between these two proteins. Thus, Shank may cross-link Homer and PSD-95 complexes in the PSD and play a role in the signaling mechanisms of both mGluRs and NMDA receptors (Tu et al. 1999).