Published in Plant Physiology on March 14, 2013


Glycosylation is an essential post-translational protein modification. And is the transfer of a preassembled oligosaccharide to selected asparagine residues to nascent proteins in the endoplasmatic reticulum by the oligosaccaryltransferase complex, OST.
I this article, the screening of a mutant population allowed the identification one of the subunits of this protein complex. They showed that mutants in the OST3/6 gene causes overall underglycosylation of certain proteins such as EFR and KOR1, affecting their biogenesis and function. The mutation also results in activation of the unfolded protein response (UPR) and causes hypersensitivity to osmotic stress, both functions that are related with other subunits of the OST complex. Consistent with data showing the importance of OST3/6 in protein glycosylation, they also found coexpression of OST3/6 gene and also protein interaction with other OST subunits. Furthermore, the authors also showed that OST3/6 is localized in the ER. Together, OST3/6 seems to function in the plant OST complex, and is required for efficient glycosylation of specific glycoproteins involved in different physiological processes.