∞ generated and posted on 2016.12.24 ∞
Means by which cells can rapidly acquire new phenotypic capabilities.
Protein activation is particularly employed with enzymes and can involve covalent modification such as phosphorylation. Not only does it allow for rapid changes in cell phenotype/physiology – since gene expression is not directly required to acquire the new function – but if reversible can save the cell energy by retaining to-be-used proteins rather than degrading them only to resynthesize. That is, proteins often can be activated, inactivated, and then activated against.
Once sees protein activation particularly in signal transduction cascades. In addition, protein activation is particularly important with eukaryotic cells for which delays between transcription and translation, due to their segregation, can be substantially larger than with prokaryotic cells.