HUMAN GLYCOPROTEINS AND DERIVED VARIANTS FROM RECOMBINANT MAMMALIAN CELLLINES

Abstract

The expression of foreign genes using recombinant DNA technology in various host systems has permitted the production of human proteins of therapeutic interest in high amounts. Manyclinically important human proteins are posttranslationally modified. However, the inability of microbes to perform mammalian-type of posttranslational modifications of proteins is a major shortcoming. Alternative expression systems are insect and mammaliancells. Principle mammalian types of protein modifications are N- and O-glycosylation. Insect cells, fungi and yeasts are unable to perform the same terminal glycosylation reactions on glycoproteins as mammalian cells. Recombinant DNA technology used for the production of pharmaceutically useful polypeptides has mainly been focused on microbial expression systems (bacteria like E. coli, yeast and fungi). The advantage of microbial expression systems is the high amount of expressed protein that can be obtained. The present communication considers aspects of glycoprotein research relevant to the field of biotechnology and protein design. Results are presented that have been obtained by our group during the last four years concerning the expression of the glycoproteins human Interleukin 2 (Il-2) and Interferon-8 (IFN-8) in different mammalian cell lines, the determination of their carbohydrate residues, the effect of site-directed mutagenesis on their carbohydrate attachment sites and the insertion of peptide domains which function as acceptors for carbohydrates.