Figure 3.
Strategies to accumulate high amounts of recombinant pharmaceuticals in the ER and ER-derived oil bodies. Through the use of plant protein domains (e.g., zein domains, oleosins, or tail-anchors), multiple protein fusions have been
examined. Zein domains allow protein body formation within the ER lumen. Oleosin fusion products are first inserted into the
external monolayer of the ER bilayer and then integrated into a nascent oil body (yellow). The tail anchor “anchors” recombinant
proteins to the ER surface; upon overexpression, the ER can be commandeered in this way to develop distinct topologies that
increase the stability of recombinant proteins. The hydrophobic domains of oleosin and of tail-anchored proteins are indicated
in violet and red, respectively. Note that the N-terminal and C-terminal domains of oleosin are in the cytosol, and the very
short C-terminal sequence of the tail-anchor is instead luminal.