This chapter describes the expression of human plasminogen complementary DNA (cDNA) in lepidopteran insect cells and analysis of asparagine-linked glycosylation patterns of recombinant plasminogens. The reasons for the popularity of this approach include (1) the high levels of expression that are possible when heterologous cDNA is linked to the late polyhedrin (PH) promoter (2) the ease of screening recombinant viruses when insertion is such that the viral PH gene is strategically interrupted by the heterologous cDNA, and (3) the fact that many post- and co-translational reactions, typical of higher order eukaryotic processing events that lead to mature proteins, are found to occur in lepidopteran-based expression systems. These reactions include signal peptide cleavage, proteolysis, nuclear translocation, fatty acid acylation, phosphorylation, and N-and O-linked glycosylation. In any case, manipulation of invertebrate cell cultures can lead to exclusive levels of mammalian-type complex oligosaccharide processing, and these results provide an excellent system in which to investigate the factors that determine the nature of the types of oligosaccharides assembled on glycoproteins.
ASJC Scopus subject areas
- Molecular Biology