positive regulation of protein monoubiquitination

Definition

Target type: biologicalprocess

Any process that activates or increases the frequency, rate or extent of protein monoubiquitination. [GOC:TermGenie, PMID:21931591]

Positive regulation of protein monoubiquitination is a crucial biological process that involves the precise and controlled addition of a single ubiquitin molecule to a target protein. This modification can dramatically alter the target protein's fate and function, influencing a wide range of cellular processes.

Ubiquitin, a small 76 amino acid protein, is a highly conserved molecule found in all eukaryotes. It acts as a molecular tag that can be attached to target proteins via a complex enzymatic cascade. This cascade involves three major enzymes:

1. **E1 (Ubiquitin Activating Enzyme):** E1 activates ubiquitin by attaching it to itself in an ATP-dependent manner.
2. **E2 (Ubiquitin Conjugating Enzyme):** E2 receives the activated ubiquitin from E1 and transfers it to a cysteine residue on its active site.
3. **E3 (Ubiquitin Ligase):** E3 is the key specificity determinant in the ubiquitination process. It recognizes and binds to the target protein, bringing it into proximity with the ubiquitin-loaded E2. E3 facilitates the transfer of ubiquitin from E2 to a lysine residue on the target protein.

The process of monoubiquitination occurs when a single ubiquitin molecule is attached to the target protein. This modification can have various effects depending on the target protein and the site of ubiquitination.

**Key Functions of Positive Regulation of Protein Monoubiquitination:**

* **Protein Degradation:** Monoubiquitination can target proteins for degradation via the proteasome. In some cases, monoubiquitination can trigger the attachment of additional ubiquitin chains, leading to polyubiquitination and subsequent proteasomal degradation.
* **Protein Trafficking:** Monoubiquitination can regulate protein trafficking and localization within the cell. It can act as a signal for proteins to be sorted to specific compartments or transported across membranes.
* **Signal Transduction:** Monoubiquitination plays a critical role in signal transduction pathways by modulating the activity of signaling proteins. It can activate or inhibit signaling pathways by altering protein interactions or subcellular localization.
* **DNA Repair:** Monoubiquitination is involved in DNA repair processes by regulating the recruitment of repair proteins to sites of DNA damage.
* **Immune Response:** Monoubiquitination contributes to the regulation of immune responses by modulating the activity of immune receptors and signaling molecules.

**Regulation of Monoubiquitination:**

The process of monoubiquitination is tightly regulated by various mechanisms, including:

* **Expression and Activity of E1, E2, and E3 enzymes:** The expression and activity of these enzymes are controlled by different cellular signaling pathways and feedback mechanisms.
* **Specificity of E3 Ligases:** E3 ligases exhibit a high degree of specificity for their target proteins, ensuring that the ubiquitination process is targeted and controlled.
* **Deubiquitinating Enzymes:** Deubiquitinating enzymes (DUBs) remove ubiquitin from target proteins, counterbalancing the activity of ubiquitin ligases and fine-tuning ubiquitination levels.

**Conclusion:**

Positive regulation of protein monoubiquitination is a highly sophisticated and dynamic process that plays a vital role in maintaining cellular homeostasis and regulating a wide array of cellular functions. Understanding the molecular mechanisms underlying this process is crucial for comprehending the complexity of cellular signaling and its implications in human health and disease.'
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Proteins (1)

Compounds (8)