ABSTRACT
As expected, the crystal structures of deglycosylated hCG and FSH are very similar (7,8) and reveal that both subunits contain so-called “cystine knot structures” that are similar to some remotely related growth factor-type signaling molecules. Each subunit has elongated shape, with two -hairpin loops on one side of the central cystine knot and a single long loop on the other side. The noncovalent interaction between the two subunits is stabilized by a segment of the -subunit that extends like a “seatbelt” around the -subunit and is locked by a disulphide bridge (7,8).
