[Perspective] Quantifying protein (dis)order

Twenty-five years ago, Chothia predicted that the structural domains of all proteins can be classified into about 1000 folds (1). Later studies refined this number; however, scientists also found that some proteins or parts of proteins never assume a specific fold. These regions are called intrinsically unstructured or disordered (2). Oncogenes such as p53 or breast cancer 1 (BRCA1) contain long disordered stretches, and aggregation of the disordered α-synuclein is thought to underlie Parkinson