Enables PDZ domain binding activity. Predicted to be involved in several processes, including I-kappaB phosphorylation; chemical synaptic transmission; and maintenance of presynaptic active zone structure. Located in membrane; postsynaptic density; and synaptic vesicle. Is active in presynaptic active zone cytoplasmic component. Orthologous to human ERC1 (ELKS/RAB6-interacting/CAST family member 1). [provided by Alliance of Genome Resources, Apr 2022]