Thought to be involved in the organization of the cytomatrix at the nerve terminals active zone (CAZ) which regulates neurotransmitter release. Seems to act together with BSN. May recruit liprin-alpha proteins to the CAZ. Interacts with BSN, ERC1, PPFIA1, PPFIA2, PPFIA3 and PPFIA4. Interacts through its C-terminus with the PDZ domain of RIMS1. Part of a complex consisting of ERC2, RIMS1 and UNC13A. In neurons, localized to synapses, and colocalizes with PCLO. Localized to the active zone of presynaptic density (By similarity). Truncated N-terminus.