Protein partitioning in liquid-ordered (Lo) / liquid-disordered (Ld) domains

Full text: The lack of transmembrane proteins partitioned in the current lipid-only models for membrane rafts calls for close scrutiny of raft mimetics. Using small angle X-ray scattering (SAXS) and molecular dynamic simulations (MD), we determined structural and elastic parameters (spontaneous curvature, bending rigidity, Gaussian curvature modulus) for coexisting Lo/Ld domains in ternary mixtures of dioleoylphosphatidylcholine/dipalmitoylphosphatidylcholine/cholesterol and dioleoylphosphatidylcholine/ distearoylphosphatidyl-choline/cholesterol. Substituting these values into theoretical calculations, yields the energy penalty upon insertion of transmembrane proteins into Lo and Ld phases and consequently the preferred partitioning in one of these domains. We discuss our findings for different geometric protein shapes. (author)