post-translational protein modification

Definition

Target type: biologicalprocess

The process of covalently altering one or more amino acids in a protein after the protein has been completely translated and released from the ribosome. [GOC:jsg]

Post-translational protein modification (PTM) is a critical process that occurs after a protein has been synthesized by ribosomes. It refers to the enzymatic addition or removal of chemical groups to or from a protein, altering its structure, function, and stability. These modifications play crucial roles in diverse biological processes, including signal transduction, protein trafficking, DNA replication, and cell signaling.

**Types of PTMs:**

**1. Phosphorylation:** The addition of a phosphate group to a protein, typically to serine, threonine, or tyrosine residues. It is one of the most common PTMs and regulates a wide range of cellular processes, including enzyme activity, cell growth, and signal transduction.
**2. Glycosylation:** The attachment of sugar molecules to a protein. It can occur on asparagine, serine, or threonine residues and plays roles in protein folding, stability, and cell-cell interactions.
**3. Ubiquitination:** The addition of ubiquitin, a small protein, to a target protein. It can target proteins for degradation by the proteasome, regulate protein trafficking, and modulate protein-protein interactions.
**4. Acetylation:** The addition of an acetyl group to a protein, typically at lysine residues. It is involved in regulating gene expression, protein stability, and chromatin structure.
**5. Methylation:** The addition of a methyl group to a protein, often at lysine or arginine residues. It can affect protein activity, protein-protein interactions, and chromatin structure.
**6. Sumoylation:** The attachment of SUMO (small ubiquitin-like modifier) to a target protein. It regulates protein localization, stability, and interactions.
**7. Palmitoylation:** The addition of a palmitic acid fatty acid chain to a protein. It is involved in membrane targeting, protein-protein interactions, and signal transduction.
**8. Myristoylation:** The attachment of myristate, a saturated fatty acid, to a protein. It typically occurs at the N-terminal glycine residue and plays a role in membrane anchoring and protein interactions.
**9. Prenylation:** The addition of isoprenoid lipids, such as farnesyl or geranylgeranyl, to a protein. It is important for protein-membrane interactions and protein trafficking.

**Enzymes Involved in PTMs:**

PTMs are catalyzed by specific enzymes, including kinases (phosphorylation), glycosyltransferases (glycosylation), ubiquitin ligases (ubiquitination), acetyltransferases (acetylation), methyltransferases (methylation), SUMO ligases (sumoylation), palmitoyltransferases (palmitoylation), myristoyltransferases (myristoylation), and prenyltransferases (prenylation).

**Regulation of PTMs:**

PTMs are tightly regulated by a variety of factors, including cellular signaling pathways, environmental cues, and developmental stages. Changes in PTMs can lead to altered protein function and disease.

**Consequences of PTMs:**

PTMs can alter a protein's:

* **Structure:** Modifications can influence protein folding, stability, and conformation.
* **Function:** PTMs can activate or inhibit protein activity, alter substrate specificity, or change protein-protein interactions.
* **Localization:** Modifications can affect protein targeting and trafficking within the cell.
* **Stability:** PTMs can regulate protein degradation and turnover.

**Importance of PTMs:**

PTMs are essential for maintaining normal cellular function. They play crucial roles in a wide range of biological processes, including:

* **Signal transduction:** PTMs are involved in transmitting signals from the cell surface to the nucleus, regulating gene expression, and controlling cellular responses to environmental stimuli.
* **Protein trafficking:** PTMs guide proteins to their correct cellular locations, ensuring their proper function.
* **Cell cycle regulation:** PTMs control cell growth, division, and differentiation.
* **Immune response:** PTMs are critical for the activation and regulation of immune cells.
* **Disease:** Dysregulation of PTMs is linked to a variety of diseases, including cancer, neurodegenerative disorders, and metabolic diseases.

In conclusion, PTMs are dynamic and complex processes that regulate protein function and cellular activity. They are crucial for maintaining normal cellular function and are implicated in a wide range of diseases.'
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Proteins (23)

Compounds (601)