Complementary biosensors reveal different G-protein signaling modes triggered by GPCRs and non-receptor activators
Abstract
It has become evident that activation of heterotrimeric G-proteins by cytoplasmic proteins that are not GPCRs plays a role in physiology and disease. Despite sharing the same biochemical Guanine-nucleotide Exchange Factor (GEF) activity as GPCRs in vitro, the mechanisms by which these cytoplasmic proteins trigger G-protein-dependent signaling in cells have not been elucidated. Heterotrimeric G-proteins can give rise to two active signaling species, Gα-GTP and dissociated Gβγ, with different downstream effectors, but how non-receptor GEFs affect the levels of these two species in cells is not known. Here, a systematic comparison of GPCRs and three unrelated non-receptor proteins with GEF activity in vitro (GIV/Girdin, AGS1, and Ric-8A) revealed high divergence in their contribution to generating Gα-GTP and free Gβγ in cells directly measured with live-cell biosensors. These findings demonstrate fundamental differences in how receptor and non-receptor G-protein activators promote signaling in cells despite sharing similar biochemical activities in vitro.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files.
Article and author information
Author details
Funding
National Institute of General Medical Sciences (R01GM136132)
- Mikel Garcia-Marcos
National Institute of Neurological Disorders and Stroke (R01NS117101)
- Mikel Garcia-Marcos
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Volker Dötsch, Goethe University, Germany
Publication history
- Received: December 9, 2020
- Accepted: March 30, 2021
- Accepted Manuscript published: March 31, 2021 (version 1)
- Version of Record published: April 9, 2021 (version 2)
Copyright
© 2021, Garcia-Marcos
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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