General limitations on commercial production of compounds include the efficiency of synthesis and, if a complex synthesis process is involved, the efficiency of recovery. Polypeptide production is an example of the limitations that can effect commercial production. The advent of recombinant DNA techniques has enabled investigators to produce substantial amounts of desired polypeptides in a variety of expression systems, but several problems typically occur. For example, recombinant polypeptides produced by expression of heterologous genes in eukaryotic cells are often rapidly degraded by protease in the cells. Those polypeptides that do manage to accumulate when expressed in a cell are usually disruptive to the normal machinery of the cell, thereby lowering the survival rate and the polypeptide production ability of the cell.
Recombinant polypeptides can also be insoluble and unreactive without extensive manipulation.
Such fusion protein systems, however, fail to overcome the basic protein conformation problems encountered by expressing heterologous genes in a bacterial cell. The present invention relates to a novel product and process for segregating desired molecules within a cell. Aggregate molecules comprising an adhesive molecule attached to a desired product molecule are sequestered in or within a portion of a lipid bilayer in a protective manner. This configuration results in optimally active recombinant polypeptides for use in experimental, therapeutic, and diagnostic applications.