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Nucleotide exchange factor Rab3GEP requires DENN and non-DENN elements for activation and targeting of Rab27a



Richard D. Evans

Deborah A. Briggs

Marta Cantero

Lluis Montoliu

Shyamal Patel

Elena V. Sviderskaya

Aymelt Itzen

Ana C. Figueiredo

Miguel C. Seabra


Deborah Briggs


Rab GTPases are compartment-specific molecular switches that regulate intracellular vesicular transport in eukaryotes. GDP/GTP exchange factors (GEFs) control Rab activation, and current models propose that localised and regulated GEF activity is important in targeting Rabs to specific membranes. Here we investigated the mechanism of GEF function using the Rab27a-GEF, Rab3GEP, in melanocytes as a model. We show that Rab3GEP deficient melanocytes (melan-R3GKO) manifest partial disruption of melanosome dispersion, a read-out of Rab27a activation and targeting. Using rescue of melanosome dispersion in melan-R3GKO cells and effector pull-down approaches we show that the DENN domain of Rab3GEP (conserved among RabGEFs) is necessary, but insufficient, for its cellular function and GEF activity. Finally using a mitochondrial re-targeting strategy we show that Rab3GEP can target Rab27a to specific membranes in a GEF-dependent manner. We conclude that Rab3GEP facilitates the activation and targeting of Rab27a to specific membranes, but that it differs from other DENN containing RabGEFs in requiring DENN and non-DENN elements for both of these activities and by lacking compartment-specific localisation.


Sanzà, P., Evans, R. D., Briggs, D. A., Cantero, M., Montoliu, L., Patel, S., …Hume, A. N. (2019). Nucleotide exchange factor Rab3GEP requires DENN and non-DENN elements for activation and targeting of Rab27a. Journal of Cell Science, 132(9), 1-8.

Journal Article Type Article
Acceptance Date Mar 11, 2019
Online Publication Date Mar 21, 2019
Publication Date Apr 30, 2019
Deposit Date Mar 11, 2019
Publicly Available Date May 7, 2019
Journal Journal of Cell Science
Print ISSN 0021-9533
Electronic ISSN 1477-9137
Publisher Company of Biologists
Peer Reviewed Peer Reviewed
Volume 132
Issue 9
Article Number jcs212035
Pages 1-8
Keywords Organelle transport; Guanine nucleotide exchange factor; Rab27a; Rab3GEP; melanocyte
Public URL
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