7SK snRNP

Definition

Target type: cellularcomponent

A ribonucleoprotein complex that contains the 7SK snRNA. The 7SK snRNP plays a central role in RNA polymerase II elongation control by regulating the availability of active P-TEFb. [PMID:18249148, PMID:28431135]

The 7SK snRNP (small nuclear ribonucleoprotein) is a complex composed of the 7SK RNA and several associated proteins. Its cellular component can be described as follows:

1. **7SK RNA:** A small non-coding RNA molecule, approximately 300 nucleotides long. It is characterized by a unique secondary structure that forms several stem-loop structures and a pseudoknot. The 7SK RNA acts as a scaffold for the assembly of the snRNP and plays a crucial role in the regulation of transcription.

2. **Proteins:** Several proteins associate with the 7SK RNA to form the snRNP. The core proteins include:
* **La protein (La):** This protein binds to the 3' end of 7SK RNA and is essential for its stability and correct processing.
* **HEXIM1 and HEXIM2:** These proteins bind to the 7SK RNA and the P-TEFb complex (positive transcription elongation factor b). They act as inhibitors of P-TEFb activity, preventing transcription elongation.
* **MePCE (methylphosphate capping enzyme):** This enzyme adds a 5' cap to the 7SK RNA, which is important for its stability and localization.

3. **Subcellular Localization:** The 7SK snRNP is mainly localized in the **nucleus**, specifically in the **nucleoplasm**. It is also found in the cytoplasm to a lesser extent.

4. **Dynamic Interactions:** The 7SK snRNP is a dynamic complex, constantly interacting with other cellular components. It associates with the **P-TEFb complex** to regulate the transition from initiation to elongation during transcription. It also interacts with other RNA-binding proteins, such as **hnRNPs (heterogeneous nuclear ribonucleoproteins)**, involved in RNA processing and transport.

Overall, the 7SK snRNP is a complex and essential component of the cellular machinery involved in gene expression. It acts as a regulator of transcription by sequestering P-TEFb, and its dynamic interactions with other cellular components ensure proper gene expression.'
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Proteins (1)

Compounds (1)