• Jeong Ho Lee, Jinu Lee, Kyu Yeong Choi, Regine Hepp, Jae-Youn Lee, Mi Kyung Lim, Mayumi Chatani-Hinze, Paul A Roche, Dong Goo Kim, Young Soo Ahn, Chul Hoon Kim, and Katherine W Roche.
• Department of Pharmacology, Brain Research Institute, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul 120-752, Korea.
• Proc. Natl. Acad. Sci. U.S.A. 2008 Aug 26; 105 (34): 12575-80.

AbstractMetabotropic glutamate receptors (mGluRs) 1-8 are G protein-coupled receptors (GPCRs) that modulate excitatory neurotransmission, neurotransmitter release, and synaptic plasticity. PKC regulates many aspects of mGluR function, including protein-protein interactions, Ca(2+) signaling, and receptor desensitization. However, the mechanisms by which PKC regulates mGluR function are poorly understood. We have now identified calmodulin (CaM) as a dynamic regulator of mGluR5 trafficking. We show that the major PKC phosphorylation site on the intracellular C terminus of mGluR5 is serine 901 (S901), and phosphorylation of this residue is up-regulated in response to both receptor and PKC activation. In addition, S901 phosphorylation inhibits mGluR5 binding to CaM, decreasing mGluR5 surface expression. Furthermore, blocking PKC phosphorylation of mGluR5 on S901 dramatically affects mGluR5 signaling by prolonging Ca(2+) oscillations. Thus, our data demonstrate that mGluR5 activation triggers phosphorylation of S901, thereby directly linking PKC phosphorylation, CaM binding, receptor trafficking, and downstream signaling.

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