Lipoparticles are specialized VLPs that incorporate high concentrations of target membrane proteins in their native conformation. A lipoparticle usually consists of a retroviral core protein (Gag) and a conformational-complex membrane protein, co-expressed, assembled and released from host cells. Gag core proteins self-assemble at the plasma membrane, where they bud off and capture target membrane proteins (Figure 1). Since the membrane proteins within lipoparticles are derived directly from the cell surface without mechanical disruption or detergents, the native structure and orientation of the membrane proteins are retained.