Is it possible that other SNAREs can substitute for its Qbc domains in the SNARE complex to provide more versatility for the membrane fusion complex?
(A ) Cartoons of different assembly states of the trans-SNARE complex corresponding to the points indicated in B. (B ) Free energy of membrane fusion per SNARE complex (red line), a single loaded trans-SNARE complex (blue), or a single unloaded SNARE complex (black) as a function of the distance between two membrane surfaces.
Membrane fusion is a complex process assumed to proceed via a stalk intermediate, with many steps contributing to the activation energy for fusion (Jahn and Grubmuller, 2002; Kozlovsky and Kozlov, 2002).
SNARE complex dissociation (see Additional file 2-20): Afthe the membrane fusion step, the trans-SNARE complex becomes a cis-SNARE complex whose dissociation requires the ATPase Sec18p and the soluble NSF-attachment protein (Sec17p) as cofactor [ 156, 157].
To separate the SNAREs and energize them for additional instances of trans-complex assembly and membrane fusion, Sec17 binds the cis-SNARE complex, in turn recruiting Sec18.
Membrane fusion consists of a complex rearrangement of lipids and proteins that results in the merger of two lipid bilayers.
Vps45p dissociates from its monomeric syntaxin prior to formation of trans-SNARE complexes, and then re-associates following membrane fusion and the conversion of trans-SNARE complexes to cis-SNARE complexes [10], [11].
NSF assembles with SNAP and SNAREs to form a 20S SNARE fusion complex that mediates membrane fusion between vesicles [ 1].
Synaptotagmin, an important auxiliary fusion protein and the putative Ca2+ sensor during neuronal transmission, can bind to both membrane and the SNARE complex during membrane fusion.[31], [32] Remarkably, at the preferred orientation of SNARE complex that we identified, Ca2+-binding loop in synaptotagmin C2B domain points straight toward the v-membrane in the synaptotagmin/SNARE complex[9].
Multi-subunit tethering complexes control membrane fusion events in eukaryotic cells.
