Probing membrane protein properties using droplet interface bilayers

Integral membrane proteins comprise a large proportion of drug targets, yet are challenging to study in vitro due to their amphiphilic nature. Conducting useful functional in vitro studies requires an artificial membrane that can mimic the lipid environment of the biogenic membrane. Droplet interface bilayer technology provides a method to form artificial bilayers with a robustness and physicochemical complexity that has not previously been possible, facilitating more sophisticated in vitro studies of membrane proteins. This mini-review examines functional studies of membrane proteins that utilize droplet interface bilayers to date and comments on possible directions of future research. Observations from our own laboratory regarding the study of a flippase protein in droplet interface bilayers are also presented. Impact statement The paper presents a comprehensive review of integral membrane protein studies utilizing droplet interface bilayers. Droplet interface bilayers are a novel method of constructing artificial lipid bilayers with enhanced stability and physicochemical complexity compared to existing methods. Their unique morphology also suggests applications in the construction of synthetic biological systems and protocells. As well as serving as a guide to in vitro membrane protein functional studies using droplet interface bilayers in the literature to date, a novel in vitro study of a flippase protein in a droplet interface bilayer is presented.