INTRINSICALLY DISORDERED PROTEINS: REVISITING THE STRUCTURE-FUNCTION PARADIGM

Almost a decade ago, the widely accepted and acknowledged sequence-structure-function paradigm faced a major challenge. Proteins were believed to be functional only when in structured/folded state with a well-defined and stable three dimensional conformation. Denatured proteins were found to loose function upon losing their structure. Though there were some indications about flexibility linked functionality of the proteins, it largely remained unnoticed till the beginning of this millennium. The discovery of intrinsically disordered proteins (also known as intrinsically unstructured, natively disordered, natively unfolded proteins) has provided new insights and explanations into functionality of many proteins. Intrinsically disordered proteins (IDPs) evolve rapidly and are particularly abundant in eukaryotes. They are associated with signaling, regulation and control pathways. Bioinformatics approaches are now widely used for quick and efficient identification of such proteins even at the proteome levels. This chapter highlights evolutionary trends and functional significance of IDPs, along with the methods to study intrinsically disordered regions.