Hemifusion arrest by complexin is relieved by Ca2+-synaptotagmin I.
Synaptic transmission relies on an exquisitely orchestrated series of protein-protein interactions. Here we show that fusion driven by neuronal SNAREs is inhibited by the regulatory protein complexin. Furthermore, inner-leaflet mixing is strongly impaired relative to total lipid mixing, indicating that inhibition by complexin arrests fusion at hemifusion. When the calcium sensor synaptotagmin is added in the presence of calcium, inhibition by complexin is relieved and full fusion rapidly proceeds.
Schaub
Johanna R
JR
Department of Biochemistry and Cell Biology, Rice University, 6100 Main Street MS-140, Houston, Texas 77005, USA.
Lu
Xiaobing
X
Doneske
Blair
B
Shin
Yeon-Kyun
YK
McNew
James A
JA
D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D002118:Calcium / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D047468:Immunoprecipitation; D008081:Liposomes / Q000378:metabolism; D008561:Membrane Fusion / Q000502:physiology; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D050600:SNARE Proteins / Q000235:genetics / Q000378:metabolism; D009435:Synaptic Transmission; D050863:Synaptotagmin I / Q000235:genetics / Q000378:metabolism*
D033942:Adaptor Proteins, Vesicular Transport; D029721:Drosophila Proteins; D008081:Liposomes; D009419:Nerve Tissue Proteins; D050600:SNARE Proteins; D050863:Synaptotagmin I; C095992:complexin I; D002118:Calcium