TY - JOUR T1 - Postsynaptic Density-93 Interacts with the δ2 Glutamate Receptor Subunit at Parallel Fiber Synapses JF - The Journal of Neuroscience JO - J. Neurosci. SP - 3926 LP - 3934 DO - 10.1523/JNEUROSCI.19-10-03926.1999 VL - 19 IS - 10 AU - Katherine W. Roche AU - C. Dune Ly AU - Ronald S. Petralia AU - Ya-Xian Wang AU - Aaron W. McGee AU - David S. Bredt AU - Robert J. Wenthold Y1 - 1999/05/15 UR - http://www.jneurosci.org/content/19/10/3926.abstract N2 - The glutamate receptor subunit δ2 has a unique distribution at the parallel fiber–Purkinje cell synapse of the cerebellum, which is developmentally regulated such that δ2 occurs at both parallel fiber synapses and climbing fiber synapses early in development but is restricted to parallel fiber synapses in adult animals. To identify proteins that might be involved in the trafficking or docking of δ2 receptors, we screened a yeast two-hybrid library with the cytosolic C terminus of δ2 and isolated a member of the postsynaptic density (PSD)-95 family of proteins, which are known to interact with the extreme C termini of NMDA receptors. We find that δ2 binds specifically to PSD-93, which is enriched in Purkinje cells. In addition, PSD-93 clusters δ2 when they are coexpressed in heterologous cells, and clustering is disrupted by point mutations of δ2 that disrupt the δ2–PSD-93 interaction. Ultrastructural localization of PSD-93 and δ2 shows they are colocalized at parallel fiber synapses; however, PSD-93 also is present at climbing fiber synapses of the adult rat, where δ2 is not found, indicating that the presence of PSD-93 alone is not sufficient for determining the synaptic expression of δ2. ER -