Positive regulator of dendritic spine morphogenesis and density. Required for the maintenance of excitatory synaptic transmission. Binds phosphatidylinositol 4,5-bisphosphate. Interacts (via C-terminus) with DLG1, DLG2, DLG3 and DLG4/PSD95. Interacts (via N-terminus) with ARHGEF7; the interaction is mediated by the PDZ domain (PubMed:19118189). Interacts with GPSM2 (via TPR repeat region) (PubMed:25664792). The FERM domain mediates the interaction with phosphatidylinositol 4,5-bisphosphate. The disease is caused by variants affecting the gene represented in this entry.