Functional Amyloids

Amyloids are cross β-sheet-rich peptide or protein aggregates normally thought of as bad actors that cause diseases such as Alzheimer's. But in the past few years, a number of amyloids with normal biological functions have been identified. Roland Riek of the Swiss Federal Institute of Technology, Zurich, and coworkers have added to the tally with the discovery of yet another functional amyloid (Science, DOI: 10.1126/science.1173155). They report that hormones produced by the endocrine system adopt amyloid-like cross β-sheet-rich conformations when they are stored in granules in the Golgi complex of cells. The fibrils formed by the hormones are capable of disassembling to release hormone molecules when they are needed. Riek and coworkers note that "the presence of many functional amyloids in the body, together with the apparent tight link between functional and disease-associated amyloids in their processing, biophysical, and biochemical properties, require a rethinking of the relationship between aggregation and function of polypeptides, and the correlation between amyloid aggregation and toxicity."