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Quantitative analysis of synaptic vesicle Rabs uncovers distinct yet overlapping roles for Rab3a and Rab27b in Ca2+-triggered exocytosis.

Authors: Pavlos, Nathan J  Grønborg, Mads  Riedel, Dietmar  Chua, John J E  Boyken, Janina  Kloepper, Tobias H  Urlaub, Henning  Rizzoli, Silvio O  Jahn, Reinhard 
Citation: Pavlos NJ, etal., J Neurosci. 2010 Oct 6;30(40):13441-53. doi: 10.1523/JNEUROSCI.0907-10.2010.
Pubmed: (View Article at PubMed) PMID:20926670
DOI: Full-text: DOI:10.1523/JNEUROSCI.0907-10.2010

Rab GTPases are molecular switches that orchestrate protein complexes before membrane fusion reactions. In synapses, Rab3 and Rab5 proteins have been implicated in the exo-endocytic cycling of synaptic vesicles (SVs), but an involvement of additional Rabs cannot be excluded. Here, combining high-resolution mass spectrometry and chemical labeling (iTRAQ) together with quantitative immunoblotting and fluorescence microscopy, we have determined the exocytotic (Rab3a, Rab3b, Rab3c, and Rab27b) and endocytic (Rab4b, Rab5a/b, Rab10, Rab11b, and Rab14) Rab machinery of SVs. Analysis of two closely related proteins, Rab3a and Rab27b, revealed colocalization in synaptic nerve terminals, where they reside on distinct but overlapping SV pools. Moreover, whereas Rab3a readily dissociates from SVs during Ca(2+)-triggered exocytosis, and is susceptible to membrane extraction by Rab-GDI, Rab27b persists on SV membranes upon stimulation and is resistant to GDI-coupled Rab retrieval. Finally, we demonstrate that selective modulation of the GTP/GDP switch mechanism of Rab27b impairs SV recycling, suggesting that Rab27b, probably in concert with Rab3s, is involved in SV exocytosis.

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RGD Object Information
RGD ID: 13432355
Created: 2017-09-27
Species: All species
Last Modified: 2017-09-27
Status: ACTIVE



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