Intrinsically Unstructured Proteins

Intrinsically unstructured proteins, often referred to as naturally unfolded proteins or disordered proteins, are proteins characterized by lack of stable tertiary structure when the protein exists as an isolated polypeptide chain (a subunit) under physiological conditions in vitro. The discovery of intrinsically unfolded proteins challenged the traditional protein structure paradigm, which states that a specific well-defined structure was required for the correct function of a protein and that the structure defines the function of the protein. This is clearly not the case for intrinsically unfolded proteins that remain functional despite the lack of a well-defined structure. Such proteins, in some cases, can adopt a fixed three dimensional structure after binding to other macromolecules.