Synaptic Ménage à Trois Elisabetta Furlanis, Peter Scheiffele  Neuron  Volume 90, Issue 4, Pages 665-667 (May 2016) DOI: 10.1016/j.neuron.2016.05.007 Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 1 Neurexin Diversity and Tripartite C1q-NTR-Neurexin Complexes at Synapses (A) Schematic representation of the mouse Nrxn3 gene (not to scale). Two independent transcripts arise from the alpha and beta promoters (black arrows). Constitutive exons in gray; alternative exons and alternative acceptor/donor sites in red. Alternatively spliced segments are numbered (AS1–AS6). (B) Model of neurexin-C1ql2/3-GluK2/GluK4 complexes at mossy fiber-CA3 synapses in the mouse hippocampus (ATD, amino-terminal domain; LBD, ligand-binding domain). Matsuda and colleagues hypothesize that presynaptic neurexin-3 beta lacking the alternative insertions at AS5 but containing sequences encoded by the alternative splice acceptor site (exon25b) serves as a presynaptic receptor for C1ql2/3 proteins. Considering that the vast majority of endogenous neurexins are alpha isoforms (Schreiner et al., 2015), both alpha and beta neurexin are displayed in the cartoon. (C) Model of neurexin-Cbln1-GluD2 complexes at parallel fiber synapses in the mouse cerebellum (based on Matsuda et al., 2010; Uemura et al., 2010). Here, interaction of Cbln1 with neurexins relies on an alternative splice insertion at the alternatively spliced segment 4. Neuron 2016 90, 665-667DOI: (10.1016/j.neuron.2016.05.007) Copyright © 2016 Elsevier Inc. Terms and Conditions