Cell adhesion protein (PubMed:15035988). Involved in synapse formation in the HSNL egg-laying motor neuron (PubMed:12628183, PubMed:15035988, PubMed:21858180, PubMed:24485456). Inhibits assembly of the SCF(sel-10) E3 ubiquitin ligase complex at synapses, and protects them from elimination (PubMed:17626846). Also required for F-actin assembly at the synaptic region and for axon branch formation (PubMed:24439377). Interacts with skr-1 (PubMed:17626846). Interacts with syg-2 (PubMed:21858180, PubMed:24485456). Interacts with the WAVE regulatory complex; the interaction leads to formation of a synaptic F-actin network that is required for synapse formation and axon branching (PubMed:24439377). Expression in head motor neurons, occasionally in HSN neurons and weakly in other cells in the vulval region (PubMed:12628183). Expressed in the primary synapse region of HSNL motor neuron (PubMed:18675916, PubMed:21858180). Localized to the primary synapse region in the vulva from early larval stage L4 to young adult stage. The first Ig-like domain is necessary for localization to the primary synapse region of HSNL motor neurons. Animals are viable, fertile and coordinated (PubMed:12628183). Defective HSN axon branching at the vulva (PubMed:12628183). Abnormal synaptic vesicle clustering in HSNL motor neuron (PubMed:12628183, PubMed:15035988). Synapses in the secondary synapse region, anterior to the vulva, are not eliminated during synapse development and persist into adulthood (PubMed:17626846). Belongs to the immunoglobulin superfamily.