The LRRTM (leucine-rich repeat (LRR) transmembrane neuronal) are a small family of paralogous LRR containing cell surface receptors. This family has four members (LRRTM 1-4) that share similar domain structure with an extracellular domain containing ten extracellular leucine-rich repeats that mediate protein-protein interactions, followed by a single transmembrane domain and a short c-terminal sequence containing a class I PDZ-domain-binding motif. LRRTMs are predominantely expressed in the nervous system. All four LRRTMs family members are post-synaptic localized and bind specifically to presynaptic alpha and beta-Neurexins (NRXNs) lacking an insert at splice site S4 (Siddiqui et al. 2010). Neuroligins bind NRXN containing or lacking an insert in S4, LRRTMs bind only NRXNs lacking an insert in this splicing site (de Wit et al. 2009, Ko et al. 2009).
de Wit, J,