The function of NRXN1 (neurexin 1, ENSG00000179915) is as follows. Cell surface protein involved in cell-cell-interactions, exocytosis of secretory granules and regulation of signal transmission. Function is isoform-specific. Alpha-type isoforms have a long N- terminus with six laminin G-like domains and play an important role in synaptic signal transmission. Alpha-type isoforms play a role in the regulation of calcium channel activity and Ca(2+)-triggered neurotransmitter release at synapses and at neuromuscular junctions. They play an important role in Ca(2+)-triggered exocytosis of secretory granules in pituitary gland. They may affect their functions at synapses and in endocrine cells via their interactions with proteins from the exocytotic machinery. Likewise, alpha-type isoforms play a role in regulating the activity of postsynaptic NMDA receptors, a subtype of glutamate-gated ion channels. Both alpha-type and beta-type isoforms may play a role in the formation or maintenance of synaptic junctions via their interactions (via the extracellular domains) with neuroligin family members, CBLN1 or CBLN2. In vitro, triggers the de novo formation of presynaptic structures. May be involved in specification of excitatory synapses. Alpha-type isoforms were first identified as receptors for alpha-latrotoxin from spider venom. . Neuronal cell surface protein involved in cell recognition and cell adhesion by forming intracellular junctions through binding to neuroligins (By similarity). Plays a role in formation of synaptic junctions (By similarity). Functions as part of a trans-synaptic complex by binding to cerebellins and postsynaptic GRID1. This interaction helps regulate the activity of NMDA and AMPA receptors at hippocampal synapses without affecting synapse formation. NRXN1B-CBLN2- GRID1 complex transduce presynaptic signals into postsynaptic NMDAR response (By similarity). {ECO:0000250|UniProtKB:P0DI97, ECO:0000250|UniProtKB:Q63373}.