Enables kinase activator activity. Involved in synaptic vesicle endocytosis. Acts upstream of or within negative regulation of neuron apoptotic process; positive regulation of protein kinase B signaling; and small GTPase mediated signal transduction. Located in several cellular components, including calyx of Held; clathrin-coated pit; and lamellipodium. Is active in presynaptic endocytic zone. Is expressed in several structures, including alimentary system; central nervous system; genitourinary system; sensory organ; and skeleton. Orthologous to human ITSN1 (intersectin 1). [provided by Alliance of Genome Resources, Apr 2022]