Enables GTPase activator activity; identical protein binding activity; and small GTPase binding activity. A structural constituent of postsynaptic specialization. Involved in several processes, including cellular response to epidermal growth factor stimulus; neurotransmitter receptor localization to postsynaptic specialization membrane; and regulation of signal transduction. Acts upstream of or within dendritic spine development and immunological synapse formation. Located in several cellular components, including cytosol; endosome; and neuron projection. Is active in GABA-ergic synapse; glutamatergic synapse; and postsynapse. Human ortholog(s) of this gene implicated in attention deficit hyperactivity disorder. Orthologous to human GIT1 (GIT ArfGAP 1). [provided by Alliance of Genome Resources, Apr 2022]