Enables transmembrane transporter binding activity. Acts upstream of or within regulation of membrane potential. Predicted to be located in membrane and synapse. Predicted to be active in cytoskeleton of presynaptic active zone and presynaptic membrane. Is expressed in adrenal gland; brain; cerebral cortex; prostate gland; and testis. Orthologous to human RIMS3 (regulating synaptic membrane exocytosis 3). [provided by Alliance of Genome Resources, Apr 2022]