Format

Send to

Choose Destination
Nature. 2003 Dec 4;426(6966):559-63. Epub 2003 Nov 23.

Synaptotagmin I is necessary for compensatory synaptic vesicle endocytosis in vivo.

Author information

1
Department of Biochemistry and Biophysics, Program in Neuroscience, University of California, San Francisco, 513 Parnassus Avenue, San Francisco, California 94143, USA.

Abstract

Neurotransmission requires a balance of synaptic vesicle exocytosis and endocytosis. Synaptotagmin I (Syt I) is widely regarded as the primary calcium sensor for synaptic vesicle exocytosis. Previous biochemical data suggest that Syt I may also function during synaptic vesicle endocytosis; however, ultrastructural analyses at synapses with impaired Syt I function have provided an indirect and conflicting view of the role of Syt I during synaptic vesicle endocytosis. Until now it has not been possible experimentally to separate the exocytic and endocytic functions of Syt I in vivo. Here, we test directly the role of Syt I during endocytosis in vivo. We use quantitative live imaging of a pH-sensitive green fluorescent protein fused to a synaptic vesicle protein (synapto-pHluorin) to measure the kinetics of endocytosis in sytI-null Drosophila. We then combine live imaging of the synapto-pHluorins with photoinactivation of Syt I, through fluorescein-assisted light inactivation, after normal Syt I-mediated vesicle exocytosis. By inactivating Syt I only during endocytosis, we demonstrate that Syt I is necessary for the endocytosis of synaptic vesicles that have undergone exocytosis using a functional Syt I protein.

PMID:
14634669
DOI:
10.1038/nature02184
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Nature Publishing Group
Loading ...
Support Center