Interactions of GIPC with dopamine D2, D3 but not D4 receptors define a novel mode of regulation of G protein-coupled receptors.
The C-terminus domain of G protein-coupled receptors confers a functional cytoplasmic interface involved in protein association. By screening a rat brain cDNA library using the yeast two-hybrid system with the C-terminus domain of the dopamine D(3) receptor (D(3)R) as bait, we characterized a new interaction with the PDZ domain-containing protein, GIPC (GAIP interacting protein, C terminus). This interaction was specific for the dopamine D(2) receptor (D(2)R) and D(3)R, but not for the dopamine D(4) receptor (D(4)R) subtype. Pull-down and affinity chromatography assays confirmed this interaction with recombinant and endogenous proteins. Both GIPC mRNA and protein are widely expressed in rat brain and together with the D(3)R in neurons of the islands of Calleja at plasma membranes and in vesicles. GIPC reduced D(3)R signaling, cointernalized with D(2)R and D(3)R, and sequestered receptors in sorting vesicles to prevent their lysosomal degradation. Through its dimerization, GIPC acts as a selective scaffold protein to assist receptor functions. Our results suggest a novel function for GIPC in the maintenance, trafficking, and signaling of GPCRs.
Jeanneteau
Freddy
F
Unité de Neurobiologie et Pharmacologie Moléculaire INSERM U 573, Centre Paul Broca, 75014 Paris, France. jeannet@broca.inserm.fr
Diaz
Jorge
J
Sokoloff
Pierre
P
Griffon
Nathalie
N
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001921:Brain / Q000378:metabolism*; D016466:CHO Cells; D019556:COS Cells; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D006224:Cricetinae; D003412:Cricetulus; D004298:Dopamine / Q000378:metabolism; D015723:Gene Library; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D011954:Receptors, Dopamine / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C492009:GIPC1 protein, human; C492008:Gipc1 protein, rat; D009479:Neuropeptides; D011954:Receptors, Dopamine; D011994:Recombinant Proteins; D004298:Dopamine