Enables small GTPase binding activity and voltage-gated calcium channel activity involved in positive regulation of presynaptic cytosolic calcium levels. A structural constituent of presynaptic active zone. Involved in synaptic vesicle priming. Acts upstream of or within retrograde transport, endosome to Golgi. Located in GABA-ergic synapse; cytoplasm; and glutamatergic synapse. Is expressed in several structures, including genitourinary system; gut gland; oral epithelium; retina; and telencephalon. Orthologous to human ERC1 (ELKS/RAB6-interacting/CAST family member 1). [provided by Alliance of Genome Resources, Apr 2022]