Neuroligin-1 is a single-pass type I transmembrane protein which belongs to the type-B Carboxylesterase/Lipase family. Neuroligins are cell-adhesion molecules located at the postsynaptic side of the synapse. Neuroligins interact with beta-neurexins and this interaction is involved in the formation of functional synapses. Neurexins and Neuroligins are cell adhesion molecules present in excitatory and inhibitory synapses, and they are required for correct neuron network function. These proteins are found at the presynaptic and postsynaptic membranes. Neuroligin-1 is a neuronal cell surface protein which is thought to be involved in cell-cell-interactions by forming intercellular junctions through binding to beta-neurexins. It seems to play role in formation or maintenance of synaptic junctions. It triggers the de novo formation of presynaptic structures and may be involved in specification of excitatory synapses.