Post-translational modifications

Definition

Post-translational modifications (PTMs) are chemical changes that occur to a protein after it has been synthesized by ribosomes. These modifications can significantly alter a protein's function, stability, localization, and interactions with other molecules. By adding or removing specific chemical groups, PTMs play a crucial role in regulating biological processes and ensuring proteins perform their intended roles within the cell.

5 Must Know Facts For Your Next Test

1. PTMs can include phosphorylation, glycosylation, acetylation, methylation, and ubiquitination, among others.
2. These modifications can occur on specific amino acid residues within the protein, such as serine, threonine, lysine, or cysteine.
3. PTMs can influence protein-protein interactions, impacting cellular signaling pathways and metabolic processes.
4. Many diseases, including cancer and neurodegenerative disorders, are linked to dysregulation of post-translational modifications.
5. PTMs can serve as signals for cellular processes like apoptosis, DNA repair, and immune responses, making them essential for maintaining cellular homeostasis.

Review Questions

• How do post-translational modifications influence the functionality of proteins after their synthesis?
  • Post-translational modifications impact proteins by altering their structure and function after they are synthesized. For example, the addition of phosphate groups through phosphorylation can activate or deactivate enzymatic activities. Similarly, glycosylation affects protein folding and stability. These changes are crucial because they allow proteins to adapt to different cellular conditions and regulate various biological pathways effectively.
• Discuss the role of phosphorylation as a post-translational modification in signaling pathways.
  • Phosphorylation plays a vital role in cellular signaling pathways by acting as a switch that turns proteins on or off. When kinases add phosphate groups to target proteins, it can trigger conformational changes that alter their activity or interactions with other molecules. This mechanism is essential for processes like cell division and response to external stimuli, highlighting how PTMs like phosphorylation are central to maintaining cellular functions.
• Evaluate how dysregulation of post-translational modifications can contribute to disease states.
  • Dysregulation of post-translational modifications can lead to various diseases by disrupting normal protein functions. For instance, abnormal phosphorylation patterns are often found in cancer cells, where growth and survival pathways are improperly activated. Similarly, altered glycosylation can impair cell signaling and immune responses in autoimmune diseases. Understanding these connections helps researchers develop targeted therapies aimed at correcting the underlying PTM issues in various pathologies.

Related terms

Phosphorylation:

The addition of a phosphate group to a protein, often mediated by enzymes called kinases, which can activate or deactivate the protein's function.

Glycosylation: The attachment of carbohydrate groups to proteins, which can affect protein folding, stability, and recognition by other molecules.

Ubiquitination:

The process of adding ubiquitin, a small protein, to a target protein, which often marks it for degradation by the proteasome.