Abstract: The invention is directed to a method for studying or identifying a biologically active agent that binds to a membrane protein, the method comprising: (i) obtaining one or more 2D and/or 3D structures of a saposin lipoprotein particle comprising the membrane protein, (ii) modeling the binding of said biologically active agent to said membrane protein present in said saposin lipoprotein particle using said one or more 2D and/or 3D structures and/or resolving the binding sites and interactions between said biologically active agent and said membrane protein in the 2D and/or 3D structure.

Abstract: The invention relates to a process for preparing saposin lipoprotein particles, comprising a saposin-like protein, lipids and optionally a hydrophobic agent wherein the saposin-like protein or the hydrophobic agent is selectively bound to a support to allow the self-assembly of the saposin lipoprotein particles. The process of the invention comprises the step of a.) providing the hydrophobic agent and lipids, b. 1)/b.2 contacting the hydrophobic agent or the saposin-like protein with a support that is capable of selectively binding either of the two molecules to the support, c.1)/c.2) contacting the support-bound particle components with the remaining particle components, either the saposin-like protein or the hydrophobic agent, to allow for the self-assembly of the saposin lipoprotein particle on the support and d.) optionally eluting the support-bound saposin lipoprotein particles.

Abstract: The invention is directed to a process for preparing a library of saposin lipoprotein particles, wherein the particles comprise membrane components from a cell or an organelle membrane and a lipid binding polypeptide that is a saposin-like protein belonging to the SAPLIP family of lipid interacting proteins or a derivative form thereof, wherein the process comprises the steps of a) providing a mixture of crude membrane vesicles obtained from a cell or an organelle membrane; b) contacting the mixture of step a) with the lipid binding polypeptide in a liquid environment; and c) allowing for self-assembly of the particles. The invention also provides a process for preparing a purified saposin lipoprotein particle comprising the steps of preparing a library according to the process described above and the additional step of f) purifying the saposin lipoprotein particle from the library.