title: A relationship between protein kinase C phosphorylation and calmodulin binding to the metabotropic glutamate receptor subtype 7.
abstract: Metabotropic glutamate receptor subtype 7 (mGluR7) is coupled to the inhibitory cyclic AMP cascade and is selectively activated by a glutamate analogue, L-2-amino-4-phosphonobutyrate. Among L-2-amino-4-phosphonobutyrate-sensitive mGluR subtypes, mGluR7 is highly concentrated at the presynaptic terminals and is thought to play an important role in modulation of glutamatergic synaptic transmission by presynaptic inhibition of glutamate release. To gain further insight into the intracellular signaling mechanisms of mGluR7, with the aid of glutathione S-transferase fusion affinity chromatography, we attempted to identify proteins that interact with the intracellular carboxyl terminus of mGluR7. Here, we report that calmodulin (CaM) directly binds to the carboxyl terminus of mGluR7 in a Ca(2+)-dependent manner. The CaM-binding domain is located immediately following the 7th transmembrane segment. We also show that the CaM-binding domain of mGluR7 is phosphorylated by protein kinase C (PKC). This phosphorylation is inhibited by the binding of Ca(2+)/CaM to the receptor. Conversely, the Ca(2+)/CaM binding is prevented by PKC phosphorylation. Collectively, these results suggest that mGluR7 serves to cross-link the cyclic AMP, Ca(2+), and PKC phosphorylation signal transduction cascades.
authors.affiliation: Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakajima
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: T
authors.initials: T
authors.lastname: Nakayama
authors.forename: S
authors.initials: S
authors.lastname: Nakanishi
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002846:Chromatography, Affinity; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017729:Presynaptic Terminals / Q000378:metabolism; D011422:Propionates / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: C114785:2-amino-4-phosphono-propinate; D002147:Calmodulin; D011422:Propionates; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D011994:Recombinant Proteins; C102719:metabotropic glutamate receptor 7; D011493:Protein Kinase C; C108823:metabotropic glutamate receptor 4