Enables actin filament binding activity; protein kinase binding activity; and ubiquitin protein ligase binding activity. Involved in several processes, including actin cytoskeleton organization; activation of GTPase activity; and regulation of postsynapse organization. Located in dendritic spine; neuronal cell body; and postsynaptic density. Part of protein-containing complex. Is active in glutamatergic synapse and postsynapse. Orthologous to human SIPA1L1 (signal induced proliferation associated 1 like 1). [provided by Alliance of Genome Resources, Apr 2022]