Parvana Hajieva

Abstract Cellular protein homeostasis, or proteostasis, underpins the integrity, adaptability, and survival of all cells by balancing protein synthesis, folding, trafficking, and degradation. This multilayered network is sustained by coordinated actions of molecular chaperones, the ubiquitin‒proteasome system, autophagy-lysosomal pathways, and organelle-specific quality control programs.

All life uses the same 20 amino acids, but only 7-13 early amino acids seem to be indispensable to build functional proteins. Thus, what triggered the introduction of the additional amino acids? Employing quantum chemical calculations and biochemical experiments, we find that the additional amino acids have become systematically "softer" (Ralph G.

After the first demonstration that the genetic code was not universal (1), various hypotheses have been elaborated to explain how the coordinate alteration of the major components carrying the genetic code, i.e., tRNAs, aminoacyl-tRNA-synthetases, and polypeptide chain release factors, might have been accomplished during evolution (2, 3).