TAOK2 is required for spine maturation and postsynaptic Ca+2 compartmentalization TAOK2 phosphorylates the cytoskeletal GTPase Sept7 at the conserved residue T426 Sept7 phosphorylation at T426 by TAOK2 is required for dendritic spine maturation Phosphorylated Sept7 associates with and stabilizes PSD95 promoting spine maturation