Phosphorylation and calmodulin binding of the metabotropic glutamate receptor subtype 5 (mGluR5) are antagonistic in vitro.
Metabotropic glutamate receptors, which are members of a G protein-coupled receptor family, mediate the glutamate responses by coupling to the intracellular signal transduction pathway. We herein report that calmodulin (CaM) interacts with the metabotropic glutamate receptor subtype 5 (mGluR5) in a Ca2+-dependent manner in vitro. CaM is capable of binding on two distinct sites in the COOH-terminal intracellular region of the receptor with different affinities. The CaM binding domains are separated by an alternatively spliced exon cassette present in one of the splicing isoforms of mGluR5. By using fusion proteins and synthetic peptides we showed that protein kinase C phosphorylates both CaM binding regions. This phosphorylation is inhibited by the binding of CaM to the receptor, and conversely the binding is inhibited by the phosphorylation. These antagonisms of the CaM binding and phosphorylation thus suggest the possibility that they regulate the receptor responses in vivo.
Minakami
R
R
School of Health Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-82, Japan.
Jinnai
N
N
Sugiyama
H
H
D000595:Amino Acid Sequence; D000818:Animals; D002147:Calmodulin / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
D002147:Calmodulin; C578936:Grm5 protein, mouse; D064529:Receptor, Metabotropic Glutamate 5; D018094:Receptors, Metabotropic Glutamate; D011993:Recombinant Fusion Proteins; D011493:Protein Kinase C