Weimer RM, Richmond JE, Davis WS, Hadwiger G, Nonet ML, Jorgensen EM. Defects in synaptic vesicle docking in unc-18 mutants.
Nat Neurosci 2003;
6:1023-30. [PMID:
12973353 PMCID:
PMC3874415 DOI:
10.1038/nn1118]
[Citation(s) in RCA: 201] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Accepted: 07/15/2003] [Indexed: 11/08/2022]
Abstract
Sec1-related proteins function in most, if not all, membrane trafficking pathways in eukaryotic cells. The Sec1-related protein required in neurons for synaptic vesicle exocytosis is UNC-18. Several models for UNC-18 function during vesicle exocytosis are under consideration. We have tested these models by characterizing unc-18 mutants of the nematode Caenorhabditis elegans. In the absence of UNC-18, the size of the readily releasable pool is severely reduced. Our results show that the near absence of fusion-competent vesicles is not caused by a reduction in syntaxin levels, by a mislocalization of syntaxin, by a defect in fusion or by a failure to open syntaxin during priming. Rather, we found a reduction of docked vesicles at the active zone in unc-18 mutants, suggesting that UNC-18 functions, directly or indirectly, as a facilitator of vesicle docking.
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