Probing the effects of double mutations on the versatile protein ubiquitin in Saccharomyces cerevisiae.

Ubiquitin is an indispensable protein of eukaryotic origin with an extraordinarily high degree of sequence conservation. It is used to tag proteins post-translationally and the process of ubiquitination regulates the activity of the modified proteins or drives them for degradation. Double mutations produce varied effects in proteins, depending on the structural relationship of the mutated residues, their role in the overall structure and functions of a protein.