Cell surface protein involved in cell-cell-interactions. Plays a role in the formation or maintenance of synaptic junctions via its interactions (via the extracellular domains) with neurexin family members. Plays a role in synaptic signal transmission. Homodimer. Interacts with NRXN1. Interacts with GPHN and ARHGEF9. Detected at glycinergic postsynapses in retina. Detected on dendritic spines on cultured neurons. Detected in brain cortex, septum, hippocampus, striatum, olfactory bulb, retina, colliculi, brain stem, cerebellum, thymus and skeletal muscle. Detected at inhibitory synapses throughout the brain and spinal cord (at protein level). Detected in brain, spleen, lung, skeletal muscle and kidney. Mice are viable and fertile with no obvious sensory deficits or major perturbations of behavior, but show subtle changes in synaptic signal transmission and signal processing. Mice display subtle deficits in reciprocal social interactions and communication. They have reduced brain volume. Belongs to the type-B carboxylesterase/lipase family.