The modification of a protein after its synthesis defines a critical stage in gene expression control. This process encompasses a diverse array of enzymatic modifications including, but not limited to, phosphorylation, glycosylation, ubiquitination, and proteolytic cleavage. These alterations directly impact protein activity, localization, and interaction with other cellular components. For example, phosphorylation can activate or deactivate an enzyme, while ubiquitination often signals a protein for degradation.
This regulatory layer offers cells a rapid and reversible mechanism to respond to environmental cues and developmental signals. It allows for fine-tuning of protein function independently of transcriptional or translational rates. Historically, the understanding of this type of regulation has revealed intricate pathways involved in cellular signaling, protein turnover, and disease pathogenesis. The ability to modulate protein function quickly is essential for maintaining cellular homeostasis and responding to dynamic changes.
