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SNAREs pp 323–331Cite as

Real-Time Fluorescence Detection of Calcium Efflux During Vacuolar Membrane Fusion

Part of the Methods in Molecular Biology book series (MIMB,volume 1860)


During in vitro homotypic yeast vacuole fusion Ca2+ is transported into and out of the organelle lumen. In vitro, Ca2+ is taken up from the medium by vacuoles upon the addition of ATP. During the docking stage of vacuole fusion Ca2+ is effluxed from the lumen upon the formation of trans-SNARE complexes between vesicles. Here we describe a real-time fluorescence-based assay to monitor the transport of this cation using purified organelles. Extraluminal Ca2+ is detected when the cation binds the low-affinity fluorescent dye Fluo-4 dextran. This allows for the use of a 96-well microtiter plate to be read in a fluorescence plate reader. Thus, in addition to a curve of calibrated Ca2+ standards, up to 91 experimental conditions can be monitored in a single microplate using this method.

Key words

  • Membrane fusion
  • Membrane trafficking
  • Ca2+ efflux
  • Fluorescence
  • Yeast vacuole

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This work was supported in part by NIH grant GM101132 to RAF.

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Correspondence to Rutilio Fratti .

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Miner, G.E., Fratti, R. (2019). Real-Time Fluorescence Detection of Calcium Efflux During Vacuolar Membrane Fusion. In: Fratti, R. (eds) SNAREs. Methods in Molecular Biology, vol 1860. Humana Press, New York, NY.

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  • Publisher Name: Humana Press, New York, NY

  • Print ISBN: 978-1-4939-8759-7

  • Online ISBN: 978-1-4939-8760-3

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