 However, only a relatively small number of proteins are linked to proteopathic disorders, possibly due to structural idiosyncrasies of the vulnerable proteins.For example, proteins that are normally unfolded or relatively unstable as monomers (that is, as single, unbound protein molecules) are more likely to misfold into an abnormal conformation.In nearly all instances, the disease-causing molecular configuration involves an increase in beta-sheet secondary structure of the protein.