Oleosin

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Oleosins are structural proteins found in oil bodies, a type of organelle found in plant cells. They are found in plant parts with high oil content that undergo extreme desiccation as part of their maturation process, and help stabilize the bodies.^[1]

Oleosins comprise of three parts. The N- and C-terminal domains are amphipathic, whereas the middle part is strongly hydrophobic. Models show oleosins having a hairpin-like hydrophobic shape that is inserted inside the triacylglyceride (TAG), while the hydrophilic parts are left outside oil bodies. ^[2]

Oleosins have been found on oil bodies of seeds, tapetum cells, and pollen but not fruits. Instead of a stabilizer of oil bodies, oleosins are believe to be involved in water-uptaking of pollen on stigma.

[edit] Use in Purification of Recombinant Protein

Oleosins provide an easy way of purifying proteins which have been produced recombinantly in plants. If the protein is made as a fusion protein with oleosin and a protease recognition site is incorporated between them, the fusion protein will sit in the membrane of the oil body, which can be easily isolated by centrifugation. The oil droplets can then be mixed with aqueous medium again, and oleosin cleaved from the protein of interest. Centrifugation will cause two phases to separate again, and the aqueous medium now contains the purified protein.

[edit] References

1. ^ Hsieh, Kai; Anthony H.C. Huang (September 2005). "Lipid-rich tapetosomes in Brassica tapetum are composed of oleosin-coated oil droplets and vesicles, both assembled in and then detached from the endoplasmic reticulum". The Plant Journal 43 (6): 889–99. doi:10.1111/j.1365-313X.2005.02502.x. PMID 17307923. 
2. ^ oleosin