Sybindin is a physiological syndecan-2 ligand on dendritic spines, the small protrusions on the surface of dendrites that receive the vast majority of excitatory synapses [1].

1: Synbindin, A novel syndecan-2-binding protein in neuronal dendritic spines. Ethell IM, Hagihara K, Miura Y, Irie F, Yamaguchi Y; J Cell Biol 2000;151:53-68. PMID:11018053