The increased surface accessibility for cis compared with trans lipids is likely a boon for peripheral membrane proteins that act on membrane lipids, such as Cti. Our results indicate that cis lipids would readily present their double bonds to the membrane surface where they would be accessible to subsequent protein activity, including to make natural products. By contrast, the relatively inaccessible trans acyl tails would most likely need to be recognized by transmembrane proteins. Thus, enzymatic chemistry of trans acyl tails would likely be slower, as peripheral membrane proteins are smaller and thus would diffuse faster than larger transmembrane proteins would. However, this is not reflected in Fig. as we are only considering membrane-membrane contributions to the pressure profile, allowing us to quantify a surface tension.