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. Author manuscript; available in PMC: 2013 May 31.
Published in final edited form as: Nat Struct Mol Biol. 2011 Jul 24;18(8):934–940. doi: 10.1038/nsmb.2103

Figure 4.

Figure 4

The switch in CPXacc position is necessary for Synaptotagmin-Ca2+ to trigger fusion. (a) Clamping of SNARE-mediated fusion by CPX and the reversal of the clamp by Synaptotagmin-Ca2+ in the presence of Phosphoinositol-Phospholipase C (PI-PLC) in wild-type (WT) VAMP2, VAMP2-D64A, VAMP2-D65A and VAMP-3xDA as measured in a cell-cell fusion assay. The effect of the superclamp CPX (scCPX; CPX D27L, E34F, R37A) on wild-type VAMP2 is shown for comparison. (b) Kinetics of the reversal of the CPX clamp by Syanptotagmin-Ca2+. The cell fusion recovery was carried out at 1mM free Ca2+ and the samples were fixed at the indicated time point after the addition of Ca2+. Averages and standard deviation of 2–3 independent experiments are shown