Reply to Comment on "Elastic Membrane Deformations Govern Interleaflet Coupling of Lipid-Ordered Domains"
Sprache des Titels:
Our recent publication in this journal  challenges the concept that domains in opposing membrane leaflets are in register because of interactions at a membrane midplane. Compelled by the lack of direct experimental proof for (i) midplane interaction via an overhang  or (ii) LO and LD phases repelling each other  we propose that minimization of line tension ? drives registration (R) . We dismiss antiregistration (AR) as an unlikely event because its twofold larger domain area translates into a 2?-fold larger boundary length. Moreover, the line tensions at the LD/LD?LD/LO and LO/LO?LD/LO interfaces (Cartoon 1), ?DD and ?OO, respectively, exceed the line tension at the LD/LD?LO/LO interface, ?R rendering the elastic energy WR of the registered state smaller than the elastic energy WAR of the antiregistered state. Consequently, registration is energetically favorable. Also, ?R > ?DD, ?OO because an isolated LD/LO boundary in only one leaflet leads to membrane bending. As readily observed in the Cartoon, for the membrane to remain flat, a substantial torque must be applied or an LD/LO boundary must be created in the upper monolayer to oppose the LD/LO boundary in the lower monolayer.