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Identification of a Phosphorylation Site for Calcium/Calmodulindependent Protein Kinase II in the NR2B Subunit of the N-Methyl-D-aspartate Receptor

Omkumar, Ramakrishnapillai V. and Kiely, Melinda J. and Rosenstein, Alan J. and Min, Kyung-Tai and Kennedy, Mary B. (1996) Identification of a Phosphorylation Site for Calcium/Calmodulindependent Protein Kinase II in the NR2B Subunit of the N-Methyl-D-aspartate Receptor. Journal of Biological Chemistry, 271 (49). pp. 31670-31678. ISSN 0021-9258. http://resolver.caltech.edu/CaltechAUTHORS:OMKjbc96

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Abstract

The N-methyl-D-aspartate (NMDA) subtype of excitatory glutamate receptors plays critical roles in embryonic and adult synaptic plasticity in the central nervous system. The receptor is a heteromultimer of core subunits, NR1, and one or more regulatory subunits, NR2A-D. Protein phosphorylation can regulate NMDA receptor function (Lieberman, D. N., and Mody, I. (1994) Nature 369, 235-239; Wang, Y. T., and Salter, M. W. (1994) Nature 369, 233-235; Wang, L.-Y., Orser, B. A., Brautigan, D. L., and MacDonald, J. F. (1994) Nature 369, 230-232). Here we identify a major phosphorylation site on subunit NR2B that is phosphorylated by Ca2+/calmodulin-dependent protein kinase II (CaM kinase II), an abundant protein kinase located at postsynaptic sites in glutamatergic synapses. For the initial identification of the site, we constructed a recombinant fusion protein containing 334 amino acids of the C terminus of the NR2B subunit and phosphorylated it with CaM kinase II in vitro. By peptide mapping, automated sequencing, and mass spectrometry, we identified the major site of phosphorylation on the fusion protein as Ser-383, corresponding to Ser-1303 of full-length NR2B. The Km for phosphorylation of this site in the fusion protein was ~50 nM, much lower than that of other known substrates for CaM kinase II, suggesting that the receptor is a high affinity substrate. We show that serine 1303 in the full-length NR2B and/or the cognate site in NR2A is a major site of phosphorylation of the receptor both in the postsynaptic density fraction and in living hippocampal neurons.


Item Type:Article
Additional Information:©1996 by The American Society for Biochemistry and Molecular Biology, Inc. (Received for publication, July 2, 1996, and in revised form, September 9, 1996) We thank Dr. Gary Hathaway and Dirk Krapf of the Caltech Protein/Peptide Micro Analytical Laboratory, and Leslie Schenker and Frank Asuncion for valuable assistance with this work. This work was supported by National Institutes of Health Grants NS17660 and NS28710 and National Institute of Mental Health Grant MH49176. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
Record Number:CaltechAUTHORS:OMKjbc96
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:OMKjbc96
Alternative URL:http://www.jbc.org/cgi/content/abstract/271/49/31670
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ID Code:4678
Collection:CaltechAUTHORS
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Deposited On:02 Sep 2006
Last Modified:26 Dec 2012 09:00

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