DEVELOPMENTAL REGULATION OF TYROSINE PHOSPHORYLATION OF THE NR2D NMDAGLUTAMATE-RECEPTOR SUBUNIT IN RAT CENTRAL-NERVOUS-SYSTEM

A subunit-specific antibody against the N-methyl-D-aspartate (NMDA) re ceptor NR2D protein along with an antiphosphotyrosine antibody were em ployed to examine the developmental profile of the tyrosine phosphoryl ation of NR2D and its regulation by a protein phosphatase inhibitor in rat brain. NMDA receptor proteins from the thalamus at postnatal days 1, 7, 21, and 49 were solubilized under denaturing conditions and use d in immunoprecipitations with these antibodies followed by quantitati ve immunoblot analysis of NR2D protein in the resulting immunopellets. The results indicate that the NR2D subunit is tyrosine phosphorylated in the brain. The quantified data examining the developmental profile of tyrosine phosphorylation of NR2D in the thalamus show that the lev el of tyrosine phosphorylation of NR2D protein increases five- to sixf old during development. In addition, the protein phosphatase inhibitor pervanadate (vanadyl hydroperoxide) was found to increase tyrosine ph osphorylation of NR2D subunit threefold in brain slices, implying an a ctive cycle of phosphorylation and dephosphorylation in situ. These st udies demonstrate developmentally regulated tyrosine phosphorylation o f NR2D protein in vivo, suggesting that tyrosine phosphorylation may b e important for regulating the functions of this NMDA receptor subunit in the mammalian central nervous system.