PARTIALLY DEGLYCOSYLATED HUMAN CHORIOGONADOTROPIN, STABILIZED BY INTERSUBUNIT DISULFIDE BONDS, SHOWS FULL BIOACTIVITY

Several studies indicate that in human choriogonadotropin the N-linked oligosaccharide at position 52 of the alpha-subunit is important for bioactivity. We have generated choriogonadotropin mutants in which the alpha 52 glycosylation site is removed and the alpha and beta subunit s art covalently linked by intersubunit disulfide bonds. These mutants display wild-type receptor binding and bioactivity. Furthermore, we s how that removal of the alpha 52 sugar leads to instability of heterod imeric choriogonadotropin. Therefore, we conclude that the alpha 52 ol igosaccharide of choriogonadotropin is net involved in signal transduc tion, but in the stability of the heterodimer.