Hypo-glycosylated hFSH21/18 (possesses FSHβ21 and FSHβ18bands) was isolated from hLH preparations by immunoaffinity chromatography followed by gel filtration. Fully-glycosylated hFSH24 was prepared by combining the fully-glycosylated FSHβ24 variant with hCGα and isolating the heterodimer. The hFSH21/18 glycoform preparation was significantly smaller than the hFSH24 preparation and possessed 60% oligomannose glycans, which is unusual for hFSH. Hypo-glycosylated hFSH21/18 was 9- to 26-fold more active than fully-glycosylated hFSH24 in FSH radioligand assays. Significantly greater binding of 125I-hFSH21/18 tracer than hFSH24 tracer was observed in all competitive binding assays. In addition, higher binding of hFSH21/18 was noted in association and saturation binding assays, in which twice as much hFSH21/18 was bound as hFSH24. This suggests that more ligand binding sites are available to hFSH21/18 in FSHR than to hFSH24. Hypo-glycosylated hFSH21/18 also bound rat FSHRs more rapidly, exhibiting almost no lag in binding, whereas hFSH24 specific binding proceeded very slowly for almost the first hour of incubation.
All Science Journal Classification (ASJC) codes
- Molecular Biology