Enables several functions, including protein C-terminus binding activity; protein domain specific binding activity; and signaling receptor binding activity. Involved in positive regulation of dendritic spine development; protein-containing complex assembly; and synapse maturation. Located in dendritic spine; postsynaptic density; and postsynaptic membrane. Orthologous to human SHANK1 (SH3 and multiple ankyrin repeat domains 1). [provided by Alliance of Genome Resources, Apr 2022]