Characterization of Fyn-mediated Tyrosine Phosphorylation Sites on GluRε2 (NR2B) Subunit of the N-Methyl-d-aspartate Receptor

• Published in: The Journal of biological chemistry 2001-01, Vol.276 (1), p.693-699
• Main Authors: Nakazawa, Takanobu, Komai, Shoji, Tezuka, Tohru, Hisatsune, Chihiro, Umemori, Hisashi, Semba, Kentaro, Mishina, Masayoshi, Manabe, Toshiya, Yamamoto, Tadashi
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M008085200

The N-methyl-d-aspartate (NMDA) receptors play critical roles in synaptic plasticity, neuronal development, and excitotoxicity. Tyrosine phosphorylation of NMDA receptors by Src-family tyrosine kinases such as Fyn is implicated in synaptic plasticity. To precisely address the roles of NMDA receptor tyrosine phosphorylation, we identified Fyn-mediated phosphorylation sites on the GluRε2 (NR2B) subunit of NMDA receptors. Seven out of 25 tyrosine residues in the C-terminal cytoplasmic region of GluRε2 were phosphorylated by Fyn in vitro. Of these 7 residues, Tyr-1252, Tyr-1336, and Tyr-1472 in GluRε2 were phosphorylated in human embryonic kidney fibroblasts when co-expressed with active Fyn, and Tyr-1472 was the major phosphorylation site in this system. We then generated rabbit polyclonal antibodies specific to Tyr-1472-phosphorylated GluRε2 and showed that Tyr-1472 of GluRε2 was indeed phosphorylated in murine brain using the antibodies. Importantly, Tyr-1472 phosphorylation was greatly reduced in fyn mutant mice. Moreover, Tyr-1472 phosphorylation became evident when hippocampal long term potentiation started to be observed, and its magnitude became larger in murine brain. Finally, Tyr-1472 phosphorylation was significantly enhanced after induction of long term potentiation in the hippocampal CA1 region. These data suggest that Tyr-1472 phosphorylation of GluRε2 is important for synaptic plasticity.