Evidence that calmodulin binding to the dopamine D2 receptor enhances receptor signaling.
The Ca2+ sensor calmodulin (CaM) regulates numerous proteins involved in G protein-coupled receptor (GPCR) signaling. CaM binds directly to some GPCRs, including the dopamine D2 receptor. We confirmed that the third intracellular loop of the D2 receptor is a direct contact point for CaM binding using coimmunoprecipitation and a polyHis pull-down assay, and we determined that the D2-like receptor agonist 7-OH-DPAT increased the colocalization of the D2 receptor and endogenous CaM in both 293 cells and in primary neostriatal cultures. The N-terminal three or four residues of D2-IC3 were required for the binding of CaM; mutation of three of these residues in the full-length receptor (I210C/K211C/I212C) decreased the coprecipitation of the D2 receptor and CaM and also significantly decreased D2 receptor signaling, without altering the coupling of the receptor to G proteins. Taken together, these findings suggest that binding of CaM to the dopamine D2 receptor enhances D2 receptor signaling.
Liu
Yong
Y
Department of Behavioral Neuroscience, Oregon Health & Science University. Portland, Oregon, USA.
Buck
David C
DC
Macey
Tara A
TA
Lan
Hongxiang
H
Neve
Kim A
KA
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002147:Calmodulin / Q000819:agonists / Q000378:metabolism* / Q000494:pharmacology*; D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D017072:Neostriatum / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism; D017448:Receptors, Dopamine D2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection
D002147:Calmodulin; D017448:Receptors, Dopamine D2; D005576:Colforsin; D000242:Cyclic AMP; D048049:Extracellular Signal-Regulated MAP Kinases