Tyrosine phosphorylation of the 2B subunit of the NMDA receptor is necessary for taste memory formation.

We aimed to test whether tyrosine phosphorylation of the NMDA receptor (NMDAR) in the insular cortex is necessary for novel taste learning. We found that in rats, novel taste learning leads to elevated phosphorylation of tyrosine 1472 of the NR2B subunit of the NMDAR and increases the interaction of phosphorylated NR2B with the major postsynaptic scaffold protein PSD-95. Injection of the tyrosine kinase inhibitor genistein directly into the insular cortex of rats before novel taste exposure prevented the increase in NR2B tyrosine phosphorylation and behaviorally attenuated taste-memory formation. Functionally, tyrosine phosphorylation of NR2B after learning was found to determine the synaptic distribution of the NMDAR, since microinjection of genistein to the insular cortex altered the distribution pattern of NMDAR caused by novel taste learning.