AbstractThe detected conformational sub‐states of an R‐SNARE peptide inserted in a lipid bilayer (see figure) give insights into the membrane fusion mechanism. The simulations are in agreement with most experimental data on the SNARE system, but differ in some details that may have a functional interest. Comparing rat and yeast sequences shows some minor differences in their behaviour.magnified imageCoarse‐grain molecular dynamics are used to look at conformational and dynamic aspects of an R‐SNARE peptide inserted in a lipid bilayer. This approach allows carrying out microsecond‐scale simulations which bring to light long‐lived conformational sub‐states potentially interesting in the context of the membrane fusion mechanism mediated by the SNARE proteins. We show that these coarse‐grain models are in agreement with most experimental data on the SNARE system, but differ in some details that may have a functional interest, most notably in the orientation of the soluble part of R‐SNARE that does not appear to be spontaneously accessible for SNARE complex formation. We also compare rat and yeast sequences of R‐SNARE and find some minor differences in their behavior.