THE PRODUCTION OF RECOMBINANT PROTEINS IN PLANTS

For recombinant proteins that are required in large quantities, plant agriculture probably represents the most cost-effective means of production. However, the absence of efficient methods for the processing of harvested plant materials and for the cost-effective purification of extracted proteins has so far limited the exploitation of plant expression systems. This problem, which is particularly acute for recombinant proteins required at high purity, is now being addressed. Thus, the application of oleosins as carrier proteins may provide a facile means of separating recombinant proteins from bulk seed proteins. Transgenic plants are being assessed for the production of a number of recombinant industrial enzymes. Significantly, the seeds from transgenic plants expressing genes encoding either phytase or alpha-amylase can be more or less directly employed as enzyme formulations for poultry feed modification and for starch liquefaction, respectively. Furthermore, transgenic seeds provide a simple means of storing and transporting recombinant enzymes. The plant-synthesised phytase and cc-amylase enzyme are active despite displaying non-native patterns of glycosylation. Transgenic plants have been shown to be capable of synthesising a wide range of recombinant antibodies and antibody fragments that are typical of those used in industrial processes and in therapy. Plants may be particularly suited to the production of complex, multimeric immunoglobulins since genes encoding the different components of these complex molecules can be combined by simple sexual crossing of individual transgenic plants.