STRICT ORDER OF (FUC TO ASN-LINKED GLCNAC) FUCOSYL-TRANSFERASES FORMING CORE-DIFUCOSYLATED STRUCTURES

In insect cells fucose can be either alpha 1,6- or alpha 1,3-linked to the asparagine-bound GlcNAc residue of N-glycans. Difucosylated glyca ns have also been found. Kinetic studies and acceptor competition expe riments demonstrate that two different enzymes are responsible for thi s alpha 1,6- and alpha 1,3-linkage of fucose. Using dansylated accepto r substrates a strict order of these enzymes can be established for th e formation of difucosylated structures. First, the alpha 1,6-fucosylt ransferase catalyses the transfer of fucose into alpha 1,6-linkage to the non-fucosylated acceptor and then the alpha 1,3-fucosyltransferase completes the difucosylation.