RT Journal Article SR Electronic T1 Mapping the cell-surface proteome underlying hippocampal mossy fiber synapse identity JF bioRxiv FD Cold Spring Harbor Laboratory SP 846816 DO 10.1101/846816 A1 Nuno ApĆ³stolo A1 Samuel N. Smukowski A1 Jeroen Vanderlinden A1 Giuseppe Condomitti A1 Vasily Rybakin A1 Jolijn ten Bos A1 Sybren Portegies A1 Kristel M. Vennekens A1 Natalia V. Gounko A1 Keimpe D. Wierda A1 Jeffrey N. Savas A1 Joris de Wit YR 2019 UL http://biorxiv.org/content/early/2019/11/18/846816.abstract AB Synaptic diversity is a key feature of neural circuits. Its underlying molecular basis is largely unknown, due to the challenge of analyzing the protein composition of specific synapse types. Here, we isolate the hippocampal mossy fiber (MF) synapse, taking advantage of its unique size and architecture, and dissect its proteome. We identify a rich cell-surface repertoire that includes adhesion proteins, guidance cue receptors, extracellular matrix (ECM) proteins, and proteins of unknown function. Among the latter, we find IgSF8, a previously uncharacterized neuronal receptor, and uncover its role in regulating MF synapse architecture and feedforward inhibition on CA3 pyramidal neurons. Our findings reveal a diverse MF synapse surface proteome and highlight the role of neuronal surface-ECM interactions in the specification of synapse identity and circuit formation.One Sentence Summary Proteomic dissection of a specific synapse