Human Multisubunit E3 Ubiquitin Ligase Required for Heterotrimeric G-Protein ?-Subunit Ubiquitination and Downstream Signaling.

G-protein-coupled receptors (GPCRs) initiate intracellular signaling events through heterotrimeric G-protein ?-subunits (G?) and the ??-subunit dimer (G??). In this study, we utilized mass spectrometry to identify novel regulators of G?? signaling in human cells. This prompted our characterization of KCTD2 and KCTD5, two related potassium channel tetramerization domain (KCTD) proteins ...
that specifically recognize G??. We demonstrated that these KCTD proteins are substrate adaptors for a multisubunit CUL3-RING ubiquitin ligase, in which a KCTD2-KCTD5 hetero-oligomer associates with CUL3 through KCTD5 subunits and recruits G?? through both KCTD proteins in response to G-protein activation. These KCTD proteins promote monoubiquitination of lysine-23 within G?1/2 in vitro and in HEK-293 cells. Depletion of these adaptors from cancer cell lines sharply impairs downstream signaling. Together, our studies suggest that a KCTD2-KCTD5-CUL3-RING E3 ligase recruits G?? in response to signaling, monoubiquitinates lysine-23 within G?1/2, and regulates G?? effectors to modulate downstream signal transduction.
Mesh Terms:
Cullin Proteins, HEK293 Cells, Heterotrimeric GTP-Binding Proteins, Humans, Potassium Channels, Signal Transduction, Ubiquitin-Protein Ligases, Ubiquitination
J Proteome Res
Date: Dec. 03, 2020
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