We have conducted unbiased molecular dynamics simulations for SMACs located between and above/below the bilayers belonging to two different organelles (see figure ). In this arrangement the intra and extra-organelle spaces are mutually exclusive (see inset in figure ) and do not share molecules neither before nor after the fusion pore has been formed (see figure ). We have induced the formation of the fusion pore from initially flat and parallel bilayers using our in-house collective variable procedure . For SMACs in the MARTINI coarse-grained space we have used the parameters developed by Prof. Orekhov (who generously shared his files with us through personal communications) to study lipid patches in the bilayer , see figure . We have used biologically relevant membranes including 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC), 1palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and the MARTINI POP2 general model for phosphatidylinositol bisphosphate lipids, corresponding to the atomistic model C16:1(9c),C18:1(9c) dioleoyl (DO-PIP 2 ) . This ternary membrane composition (POPC:POPS:POP2) is analogous to the plasma membrane used experimentally by Jahn and collaborators to trap synaptotagmin-1 to the plasma membrane in the presence of calcium.