Partially deglycosylated human choriogonadotropin, stabilized by intersubunit disulfides bonds, shows full bioactivity

Abstract

Several studies indicate that in human choriogonadotropin the N-linked oligosaccharide at position 52 of the α-subunit is important for bioactivity. We have generated choriogonadotropin mutants in which the α52 glycosylation site is removed and the α and β subunits are covalently linked by intersubunit disulfide bonds. These mutants display wild-type receptor binding and bioactivity. Furthermore, we show that removal of the α52 sugar leads to instability of heterodimeric choriogonadotropin. Therefore, we conclude that the α52 oligosaccharide of choriogonadotropin is not involved in signal transduction, but in the stability of the heterodimer.