Official websites use. Share sensitive information only on official, secure websites. Terms of Use. Over the past decade, we have observed a massive increase in the amount of information describing protein sequences from a variety of organisms.
For instance, homology detection allows for the transfer of information from well-characterized protein segments to those with similar sequences that lack annotation of molecular function.
In addition, it is likely to shed new light on molecular mechanisms of diseases that are not yet fully understood. Thus, uncharacterized protein segments are likely to be a large source of functional novelty relevant for discovering new biology. Traditionally, protein function has been viewed as critically dependent on the well-defined and folded three-dimensional structure of the polypeptide chain. This classical structureβfunction paradigm Figure 1 ; left panel has mainly been based on concepts explaining the specificity of enzymes, and on structures of folded proteins that have been determined primarily using X-ray diffraction on protein crystals.
The classical concept implies that protein sequence defines structure, which in turn determines function; that is, function can be inferred from the sequence and its structure. Even when protein sequences diverge during evolution, for example, after gene duplication, the overall fold of their structures remains roughly the same. Therefore, structural similarity between proteins can reveal distant evolutionary relationships that are not easily detectable using sequence-based methods.
Structured domains and intrinsically disordered regions IDRs are two fundamental classes of functional building blocks of proteins. The synergy between disordered regions and structured domains increases the functional versatility of proteins. Adapted with permission from ref Copyright American Association for the Advancement of Science. Classification schemes provide a guideline for systematic function assignment to proteins.
