Specificity of metabotropic glutamate receptor 2 coupling to G proteins.
Metabotropic glutamate receptor 2 (mGluR2) is a class 3 G protein-coupled receptor and an important mediator of synaptic activity in the central nervous system. Previous work demonstrated that mGluR2 couples to pertussis toxin (PTX)-sensitive G proteins. However, the specificity of mGluR2 coupling to individual members of the G(i/o) family is not known. Using heterologously expressed mGluR2 in rat sympathetic neurons from the superior cervical ganglion (SCG), the mGluR2/G protein coupling profile was characterized by reconstituting coupling in PTX-treated cells expressing PTX-insensitive mutant Galpha proteins and Gbetagamma. By employing this method, it was demonstrated that mGluR2 coupled strongly with Galphaob, Galphai1, Galphai2, and Galphai3, although coupling to Galphaoa was less efficient. In addition, mGluR2 did not seem to couple to the most divergent member of the G(i/o) family, Galphaz, although Galphaz coupled strongly to the endogenous alpha2 adrenergic receptor. To determine which Galpha proteins may be natively expressed in SCG neurons, the presence of mRNA for various Galpha proteins was tested using reverse transcription-polymerase chain reaction. Strong bands were detected for all members of the G(i/o) family (Galphao, Galphai1, Galphai2, Galphai3, Galphaz) as well as for Galpha11 and Galphas. A weak signal was detected for Galphaq and no Galpha15 mRNA was detected.
Kammermeier
Paul J
PJ
Laboratory of Molecular Physiology, National Institutes of Health, National Institute on Alcohol Abuse and Alcoholism, Rockville, Maryland, USA. pjkammer@neoucom.edu
Davis
Margaret I
MI
Ikeda
Stephen R
SR
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004594:Electrophysiology; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D037342:Pertussis Toxin / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D017783:Superior Cervical Ganglion / Q000166:cytology
D018094:Receptors, Metabotropic Glutamate; C108822:metabotropic glutamate receptor 2; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D002118:Calcium