Figure 1. A model for GluD2's role in LTD induction. GluD2 acts as a gatekeeper for LTD induction by maintaining a low phosphorylation level at Y876 of the AMPA-receptor GluA2 subunit through PTPMEG, which binds to GluD2’s C-terminus. LTD-inducing stimuli further dephosphorylate Y876 by unknown mechanisms. GluA2 Y876 dephosphorylation allows S880 to be phosphorylated by protein kinase C (PKC) and enables the glutamate receptor interacting protein (GRIP), a membrane anchoring protein, to be replaced by PICK1, leading to AMPA-receptor endocytosis and LTD.