Provided is an isolated yeast or mammalian host cell engineered to express at least one nucleic acid encoding a fusion polypeptide having beta(1,4)-N-acetylglucosaminyltransferase III activity or beta(1,4)-galactosyltransferase activity and at least one nucleic acid encoding a polypeptide having mannosidase II activity in an amount sufficient to modify the oligosaccharides in the Fc region of a polypeptide produced by said host cell, wherein said polypeptide is selected from the group consisting of a whole antibody molecule, an antibody fragment, and a fusion protein that includes a region equivalent to the Fc region of an immunoglobulin.
