Abstract
Rab3a is a small GTPase that binds selectively to secretory vesicles and switches between active, GTP-bound and inactive. GDP-bound conformations. In yeast, Rab and SM-genes interact genetically to promote vesicle targeting/fusion. We tested different Rab3a conformations and genetic interactions with the SM-gene munc18-1 on the docking function of Rab3 in mammalian chromaffin cells. We expressed Rab3a mutants locked in the GTP- or GDP-bound form in wild-type and much 18-1 null mutant cells and analyzed secretory vesicle distribution. We confirmed that wild-type Rab3a promotes vesicle docking in wild-type cells. Unexpectedly, both GTP-and GDP-locked Rab3a mutants did not promote dockling. Furthermore, wild-type. Rab3a did not promote docking in munc18-1 null cells and GTP and GDP-Rab3a both decreased the amount of docked vesicles. The results show that GTP-and GDP-locked conformations do not support a Munc 18-1 dependent role of Rabta in docking. This suggests that nucleotide cycling is required to support docking and that this action of Rab3a is upstream of Munc 18-1. © 2007 van Weering et al.
Original language | English |
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Article number | e616 |
Pages (from-to) | e616 |
Number of pages | 5 |
Journal | PLOS ONE |
Volume | 2 |
Issue number | 7 |
DOIs | |
Publication status | Published - 18 Jul 2007 |