RESUMO
G protein-coupled receptors (GPCRs) initiate an array of intracellular signaling programs by activating heterotrimeric G proteins (Gα and Gßγ subunits). Therefore, G protein modifiers are well positioned to shape GPCR pharmacology. A few members of the potassium channel tetramerization domain (KCTD) protein family have been found to adjust G protein signaling through interaction with Gßγ. However, comprehensive details on the KCTD interaction with Gßγ remain unresolved. Here, we report that nearly all the 25 KCTD proteins interact with Gßγ. In this study, we screened Gßγ interaction capacity across the entire KCTD family using two parallel approaches. In a live cell bioluminescence resonance energy transfer-based assay, we find that roughly half of KCTD proteins interact with Gßγ in an agonist-induced fashion, whereas all KCTD proteins except two were found to interact through coimmunoprecipitation. We observed that the interaction was dependent on an amino acid hot spot in the C terminus of KCTD2, KCTD5, and KCTD17. While KCTD2 and KCTD5 require both the Bric-à-brac, Tramtrack, Broad complex domain and C-terminal regions for Gßγ interaction, we uncovered that the KCTD17 C terminus is sufficient for Gßγ interaction. Finally, we demonstrated the functional consequence of the KCTD-Gßγ interaction by examining sensitization of the adenylyl cyclase-cAMP pathway in live cells. We found that Gßγ-mediated sensitization of adenylyl cyclase 5 was blunted by KCTD. We conclude that the KCTD family broadly engages Gßγ to shape GPCR signal transmission.
