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Elife. 2014 Feb 25;3:e01524. doi: 10.7554/eLife.01524.

Synaptotagmin 7 functions as a Ca2+-sensor for synaptic vesicle replenishment.

Author information

1
Department of Neuroscience, Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States.

Abstract

Synaptotagmin (syt) 7 is one of three syt isoforms found in all metazoans; it is ubiquitously expressed, yet its function in neurons remains obscure. Here, we resolved Ca(2+)-dependent and Ca(2+)-independent synaptic vesicle (SV) replenishment pathways, and found that syt 7 plays a selective and critical role in the Ca(2+)-dependent pathway. Mutations that disrupt Ca(2+)-binding to syt 7 abolish this function, suggesting that syt 7 functions as a Ca(2+)-sensor for replenishment. The Ca(2+)-binding protein calmodulin (CaM) has also been implicated in SV replenishment, and we found that loss of syt 7 was phenocopied by a CaM antagonist. Moreover, we discovered that syt 7 binds to CaM in a highly specific and Ca(2+)-dependent manner; this interaction requires intact Ca(2+)-binding sites within syt 7. Together, these data indicate that a complex of two conserved Ca(2+)-binding proteins, syt 7 and CaM, serve as a key regulator of SV replenishment in presynaptic nerve terminals. DOI: http://dx.doi.org/10.7554/eLife.01524.001.

KEYWORDS:

neurotranmission; synaptic vesicle; synaptotagmin

PMID:
24569478
PMCID:
PMC3930910
DOI:
10.7554/eLife.01524
[Indexed for MEDLINE]
Free PMC Article

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