Enables GTPase binding activity. Involved in positive regulation of GTPase activity; positive regulation of endocytosis; and synaptic vesicle endocytosis. Located in several cellular components, including T-tubule; Z disc; and axon. Is active in glutamatergic synapse. Is extrinsic component of synaptic vesicle membrane. Human ortholog(s) of this gene implicated in breast carcinoma; centronuclear myopathy 2; and prostate adenocarcinoma. Orthologous to human BIN1 (bridging integrator 1). [provided by Alliance of Genome Resources, Apr 2022]