nuclear ubiquitin ligase complex

Definition

Target type: cellularcomponent

A ubiquitin ligase complex found in the nucleus. [GOC:mah]

The nuclear ubiquitin ligase (E3) complex is a multi-protein assembly responsible for ubiquitination of target proteins within the nucleus. This complex is essential for various cellular processes, including DNA repair, transcription, and cell cycle regulation. It comprises several key components that work together to ensure efficient and specific ubiquitination:

- **E3 ligase:** The core component of the complex, which directly interacts with the target protein and catalyzes the transfer of ubiquitin from an E2 ubiquitin conjugating enzyme. Different E3 ligases exhibit specificity for particular target proteins and often contain domains that recognize specific protein motifs.

- **E2 ubiquitin conjugating enzyme:** An enzyme that carries ubiquitin and transfers it to the E3 ligase. Several E2 enzymes can participate in the ubiquitination process, contributing to the diversity of ubiquitination patterns.

- **Scaffold proteins:** Proteins that act as bridges between the E3 ligase and the target protein, enhancing the efficiency of ubiquitination by facilitating the interaction of these components. These proteins often contain domains that interact with specific protein motifs present in the target protein or the E3 ligase.

- **Regulatory proteins:** These proteins can either activate or inhibit the activity of the E3 ligase complex, ensuring that ubiquitination occurs at the appropriate time and place. These proteins can interact with the E3 ligase, the E2 enzyme, or the scaffold proteins to modulate the complex's activity.

- **Ubiquitin:** A small protein that is attached to target proteins through a process called ubiquitination. Ubiquitination can alter the protein's function, stability, or localization within the cell. The addition of multiple ubiquitin molecules (polyubiquitination) can lead to different outcomes, such as proteasomal degradation or changes in protein interactions.

The nuclear ubiquitin ligase complex is a dynamic entity whose composition can vary depending on the specific target protein and cellular context. The complex's intricate structure and precise regulation ensure that ubiquitination occurs with high specificity and efficiency, contributing to the regulation of vital nuclear processes.'
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Proteins (3)

Compounds (5)