Parathyroid hormone (PTH) is a single-chain polypeptide composed of 84 amino acids. As Preotact, it contains recombinant human parathyroid hormone which is identical to the full-length native 84-amino acid polypeptide. It is produced as a fusion protein. Post-translational processing involves the cleavage of the OmpA leader sequence, leaving the mature protein as a single-chain 84 amino-acids polypeptide (9.4 kDa) whose sequence is identical to that of the full-length native endogenous human PTH. It has no disulfide bonds and no glycosylation sites. Preotact is used in the treatment of osteoporosis in postmenopausal women at high risk of osteoporotic fractures.