IAPP and diabetes mellitus: Interestingly, more than 50% of proteins involved in protein misfolding diseases, or amyloidosis, contain disulfide bonds including the prion protein, superoxide dismutase 1 (involved in ALS), tau (taupathies and Alzheimer’s disease), islet amyloid polypeptide (IAPP; diabetes) and HEWL (systemic amyloidosis).