Structure-function relationship of follicle-stimulating hormone and its receptor

Follicle stimulating hormone (FSH) is one of the two pituitary gonadotrophins involved in the regulation of gonadal function. Structurally, this gonadotrophin is a heterodimer composed of two non-covalently associated subunits containing several heterogenous oligosaccharide residues which play an important role in both the in-vivo and in-vitro bioactivity of the hormone. Its cognate receptor, which belongs to the superfamily of the G protein-linked cell surface receptors, also displays a high degree of functional and molecular complexity. Studies employing monoclonal antibodies, synthetic peptides and/or site directed mutagenesis, have unveiled some of the multiple structural determinants involved in FSH and FSH receptor function and interaction. Despite their structural complexity, both molecules exhibit a high degree of plasticity and diversity that allows formation of distinct ligand-receptor complexes capable of selectively activating or deactivating a variety of signalling pathways. Knowledge and mapping of the structural determinants and functional epitopes for intra- and extracellular hormone action are of paramount importance not only for a better and more detailed understanding of the molecular basis of FSH action and FSH receptor function but also for the rational design of analogues with predicted properties and effects.