*3.1. Selection of Proteins*

We have selected these proteins, as we and others have collected ample evidence for their function depending on their particular structural class, which is folded and intrinsically disordered. Ubiquitin (UBQ) is a small, 76-amino acid globular protein that is found ubiquitously in the cells of all eukaryotic organisms, carrying out basic and indispensable functions in regulating protein function [20]. That is, proteins targeted for degradation are covalently modified by a mono- or poly-ubiquitin chain and are directed for degradation by the 26S proteasome, whereas other proteins labeled with a mono-ubiquitin chain enter regulatory interactions in transcription regulation, for example.

ERD10 [21], on the other hand, is a plant dehydrin that has its cellular protection function strictly linked with structural disorder [22]. Its length is 260 amino acids; it is structurally disordered by a broad range of biophysical techniques, and it functions by protecting the structural integrity of client proteins under the conditions of dehydration and other stresses.
