NMDA receptors are regulated via phosphorylation sites on receptor subunits (Mao et al., 2011). Protein kinase A (PKA) and protein kinase C (PKC) are the most studied serine and threonine kinases that upregulate NMDAR function (Cerne et al., 1993; Chen and Huang, 1992), while protein phosphatases 1 (PP1), 2A (PP2A), and 2B (PP2B) are the major protein serine/threonine phosphatases to suppress NMDAR activity (Wang et al., 1994). For protein tyrosine kinases upregulating NMDAR function, the Src family, especially Src and Fyn, are the major members of this group, while the most investigated protein tyrosine phosphatase reducing NMDAR activity is striatal-enriched protein (STEP). Recently, palmitoylation was also found to regulate NMDAR trafficking (Hayashi et al., 2009). NMDAR functions are linked to many proteins directly or indirectly including dysbindin (Tang et al., 2009), neuregulin 1 (Hahn et al., 2006), and Disc1 (Hayashi-Takagi et al., 2010; Ron, 2004).
