ARL3 activation requires the co-GEF BART and effector-mediated turnover
- Beatson Institute for Cancer Research, United Kingdom
- IMDEA Nanoscience, Spain
Abstract
The ADP-ribosylation factor-like 3 (ARL3) is a ciliopathy G-protein which regulates the ciliary trafficking of several lipid-modified proteins. ARL3 is activated by its guanine exchange factor (GEF) ARL13B via an unresolved mechanism. BART is described as an ARL3 effector which has also been implicated in ciliopathies, although the role of its ARL3 interaction is unknown. Here we show that, at physiological GTP:GDP levels, human ARL3GDP is weakly activated by ARL13B. However, BART interacts with nucleotide-free ARL3 and, in concert with ARL13B, efficiently activates ARL3. In addition, BART binds ARL3GTP and inhibits GTP dissociation, thereby stabilising the active G-protein; the binding of ARL3 effectors then releases BART. Finally, using live cell imaging, we show that BART accesses the primary cilium and colocalises with ARL13B. We propose a model wherein BART functions as a bona fide co-GEF for ARL3 and maintains the active ARL3GTP, until it is recycled by ARL3 effectors.
Data availability
All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for: Figures 1A and 1B, Figures 2B, 2C, 2D, 2E, and 2F, Figures 3A,3B, 3C, 3D, 3F, Figures 4A, 4B, and 4C and Figure 5B, 5C
Article and author information
Author details
Funding
Cancer Research UK (A17196)
- Shehab Ismail
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2021, ElMaghloob et al.
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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ARL3 activation requires the co-GEF BART and effector-mediated turnover
eLife 10:e64624.
https://doi.org/10.7554/eLife.64624
