The process culminates when vesicles are delivered and tethered to the target membrane via SNARE-mediated membrane fusion, thereby completing the final steps of exocytosis.
Also, soluble VAMP2 (Vps, amino acids 1-96), whish is often used as a competitive inhibitor for SNARE-dependent membrane fusion, showed complete inhibition of lipid mixing at 10 μM (the dark red trace in Figure 1b), further supporting the SNARE-dependency of lipid mixing.
However, intragranular ATP is highly mobile and exits promptly upon membrane fusion, even before complete expansion of the fusion pore [ 26– 29].
Now, Zick et al. have shown that three types of phospholipid molecules must be present for membrane fusion to be completed.
The SHB of gp41 is an established target for N- and C-peptide fusion inhibitors [ 16– 20] as its complete formation is crucial for complete membrane fusion and pore formation [ 13– 16].
This core structure, termed the SHB (six helix bundle) is important for complete membrane fusion and pore formation [ 13– 16].
This effect is likely to contribute to the complete membrane fusion during the late phase of fusion protein-induced fusion cascade.
(Kyoung et al., 2011; Diao et al., 2012) have shown long kinetic separation between formation of some trans-SNARE complexes and complete membrane fusion for certain spontaneous fusion events (for example, in the absence of calcium) and in the presence of both synaptotagmin and complexin; upon calcium triggering, a burst of fast fusion events were then observed.
Additionally, different membrane binding regions from membrane fusion proteins are necessary to complete the fusion process [34].
Putative mechanisms by which class I viral fusion proteins achieve membrane fusion have been proposed [1], [4], [17] [19], but complete structural evidence for the role of intermediate structures in these mechanisms has yet to be obtained.
