REGULATION OF TERMINAL GLYCOSYLATION

Abstract

Mammalian cell lines used for production of recombinant glycoproteins elaborate terminal glycosylation structures on N-linked and O-linked carbohydrate groupsthat are determined by the glycosyltransferases expressed by these cells. As many as twelve glycosyltransferase cDNAs have now been cloned by a variety of strategies (1). By expressing these glycosyltransferase cDNAs incells not normally expressing them, it is now possible to alter the cellular glycosylation machinery to produce new terminal glycosylation sequences (2,3). This principle was demonstrated by expressing the rat B-galactoside 02,6 sialyltransferase (a2,6ST) cDNA in CHOcells, which are known notto express the product of this sialyltransferase. After selection for stable expression, these cells were shown to produce Nlinked carbohydrate groups with terminal 02,6 linked sialic acid, demonstrating an altered glycosylation machinery (2).