Use of mannosamine for inducing the addition of outer arm N-acetylglucosamine onto N-linked oligosaccharides of recombinant proteins in insect cells

Glycosylation is acellular process accomplished by a series of sequential e nzymatic processing steps through the endoplasmic reticulum and Golgi appar atus with vesicle transport between the membranous organelles. The capacity for complex glycosylation is considered to be conferred by cell genetics, while the roles of nongenetic factors in protein processing are often ignor ed. It was hypothesized that the glycosyltransferase reactions in the insec t cell-baculovirus system were limited by the small supply of sugar donor c osubstrates. By adding mannosamine, the,glycosylation of a human secreted a lkaline phosphatase in Spodoptera frugiperda (Sf-21) cells was extended to include terminal N-acetylglucosamine structures which were not seen in cont rol cultures, and in Trichoplusic ni (BTI-Tn5B1-4) cells the amount of term inal N-acetylglucosamine structures was increased.