Glycosylation of glycoproteins is regulated by several factors, including glycosyltransferase enzymes, suitable acceptor sites on proteins, Dol-P levels in tissues, and oligosaccharide-protein transferase activity. Different cells express different glycosyltransferases, and some require prior action of other enzymes. Glycosylation patterns can also differ between species and cells of the same species, influencing properties like the half-life of therapeutic proteins.