The present invention relates to eukaryotic host cells having modified
oligosaccharides which may be modified further by heterologous expression
of a set of glycosyltransferases, sugar transporters and mannosidases to
become host-strains for the production of mammalian, e.g., human
therapeutic glycoproteins. The process provides an engineered host cell
which can be used to express and target any desirable gene(s) involved in
glycosylation. Host cells with modified lipid-linked oligosaccharides are
created or selected. N-glycans made in the engineered host cells exhibit
GnTIII activity, which produce bisected N-glycan structures and may be
modified further by heterologous expression of one or more enzymes, e.g.,
glycosyltransferases, sugar transporters and mannosidases, to yield
human-like glycoproteins. For the production of therapeutic proteins,
this method may be adapted to engineer cell lines in which any desired
glycosylation structure may be obtained.