Recombinant Pharmaceuticals from Plants: The Plant Endomembrane System as Bioreactor

Human lysozyme is sorted into protein bodies and storage vacuoles in transgenic rice seeds. Electron micrographs of developing seed tissue (i.e., endosperm) of non-transgenic A. and transgenic B. rice seeds. In non-transgenic tissue A. the storage proteins accumulate in ER-derived protein bodies (PB-I) and in protein storage vacuoles (PB-II). In transgenic rice expressing human lysozyme B. the recombinant protein (visualized by immunogold labeling) accumulates in both PB-I-like (arrowheads) and PB-II-like (arrows) structures. Notice the ribosomes decorating the membrane of PB-I, indicating the ER origin. [Reproduced from (60).]