3m45

Publication Abstract from PubMed

Select adhesion molecules connect pre- and postsynaptic membranes and organize developing synapses. The regulation of these trans-synaptic interactions is an important neurobiological question. We have previously shown that the synaptic cell adhesion molecules SynCAM 1 and 2 engage in homo- and heterophilic interactions and bridge the synaptic cleft to induce presynaptic terminals. Here, we demonstrate that site-specific N-glycosylation impacts the structure and function of adhesive SynCAM interactions. Through crystallographic analysis of SynCAM 2, we identified within the adhesive interface of its Ig1 domain an N-glycan on residue N60. Structural modeling of the corresponding SynCAM 1 Ig1 domain indicates that its glycosylation sites N70/N104 flank the binding interface of this domain. Mass-spectrometric and mutational studies confirm and characterize the modification of these three sites. These site-specific N-glycans affect SynCAM adhesion, yet act in a differential manner. While glycosylation of SynCAM 2 at N60 reduces adhesion, N-glycans at N70/N104 of SynCAM 1 increase its interactions. The modification of SynCAM 1 with sialic acids contributes to the glycan-dependent strengthening of its binding. Functionally, N-glycosylation promotes the trans-synaptic interactions of SynCAM 1 and is required for synapse induction. These results demonstrate that N-glycosylation of SynCAM proteins differentially affects their binding interface and implicate post-translational modification as a mechanism to regulate trans-synaptic adhesion.

N-glycosylation at the SynCAM immunoglobulin interface modulates synaptic adhesion.,Fogel AI, Li Y, Giza J, Wang Q, Lam TT, Modis Y, Biederer T J Biol Chem. 2010 Aug 25. PMID:20739279^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.