Postsynaptic MAGUK scaffold protein that links CADM1 cell adhesion molecules to core components of the postsynaptic density (By similarity). In CA1 pyramidal neurons, required for synaptic KCNN2-containing channel function and long-term potentiation expression (By similarity). Seems to negatively regulate SRC function in epithelial cells (PubMed:19665017). Can homomultimerise. Interacts with CACNG2. Interacts (via the SH3-Guanylate kinase-like sub-module) with DLG4/PSD95 and DLGAP1/GKAP. Interacts (via the PDZ domain) with CADM1 (via C-terminus) (By similarity). Interacts with KCNN2/SK2 (via N-terminal domain) (By similarity). Interacts with SRC (PubMed:19665017). Prominently expressed in the postsynaptic densities of dendritic spines, is also detected in dendritic shafts. Phosphorylated by SRC. Belongs to the MAGUK family.