Fig. 1

Map of follitropin beta-subunit cleavage sites from stomach and pancreatic proteases digestion: pepsin, trypsin, chymotrypsin. The image derives from resource web portals web.expasy.org and databases for protein sequences www.uniprot.org; www.rcsb.org/pdb/). This tool predicts cleavage sites of selected proteases in a protein sequence, in this case pepsin (Pn1.3), trypsin (Tryps), chymotrypsin (Ch_Lo). In the map, the cleavage probability of trypsin and chymotrypsin is 70 % at least. Cleavage occurs at the right side (C-terminal direction) of the marked amino acid. Specific residues for hFSH-receptor binding in the follitropin beta-subunit [48] are identify in red. The highlighted peptide sequence composed of amino acids 95–121 likely maintains the biological activity of intact FSH, based on our in silico analysis, and it was used for in vitro assay