Neuroligin-4, X-linked (NLGN4X) is also known as HNLX, KIAA1260, NLGN4, ASPGX2, AUTSX2, HLNX, HNL4X, NLGN, NLGN4, which belongs to the type-B carboxylesterase/lipase family, a neuronal cell surface proteins. NLGN4X is a homodimer, which can interacts with NRXN1 in a calcium-dependent manner and also interacts through its C-terminus with DLG4/PSD-95 third PDZ domain. Neuroligins may act as splice site-specific ligands for beta-neurexins and may be involved in the formation and remodeling of central nervous system synapses. NLGN4X is putative neuronal cell surface protein involved in cell-cell-interactions.