RNA export from nucleus

Definition

Target type: biologicalprocess

The directed movement of RNA from the nucleus to the cytoplasm. [GOC:ma]

RNA export is a tightly regulated process that ensures the proper delivery of mature messenger RNA (mRNA) from the nucleus to the cytoplasm, where it can be translated into proteins. This intricate process involves multiple steps, each facilitated by specific proteins and complexes:

1. **Transcription and Processing:** mRNA transcripts are synthesized in the nucleus by RNA polymerase II. During transcription, the nascent mRNA undergoes several modifications, including capping at the 5' end, splicing out introns, and polyadenylation at the 3' end. These modifications are essential for mRNA stability, transport, and translation.

2. **Recognition and Binding:** Once processed, mRNAs are recognized by specific nuclear export receptors (NXRs), primarily the heterodimer of nuclear export factor 1 (NXF1) and nuclear export factor 2 (NXF2). These receptors bind to specific sequences within the mRNA, including the 5' cap, the poly-A tail, and specific RNA recognition motifs (RRMs) within the mRNA molecule.

3. **Nuclear Pore Complex Translocation:** The mRNA-NXR complex interacts with the nuclear pore complex (NPC), a large protein assembly embedded in the nuclear envelope. The NPC acts as a selective gatekeeper, allowing the passage of specific molecules, including mRNAs, while excluding other molecules.

4. **RanGTP-dependent Transport:** The translocation of the mRNA-NXR complex through the NPC is driven by a small GTPase protein called Ran. In the nucleus, Ran is bound to GTP, while in the cytoplasm, it is bound to GDP. This RanGTP gradient is crucial for the export process. The interaction of RanGTP with the NXR complex triggers the release of the mRNA into the cytoplasm.

5. **Cytoplasmic Release and Translation:** Once in the cytoplasm, the mRNA is released from the NXR complex. The mRNA then associates with ribosomes, the protein synthesis machinery, and translation commences.

6. **Quality Control and Degradation:** During the entire process, there are multiple quality control checkpoints that ensure only properly processed and functional mRNAs are exported. Any aberrant or damaged mRNAs are either retained in the nucleus or targeted for degradation.

In summary, RNA export is a complex and highly regulated process that involves recognition, binding, translocation, and release of mature mRNAs from the nucleus to the cytoplasm. This intricate process ensures the efficient delivery of genetic information for protein synthesis, contributing to cellular function and development.'
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Proteins (1)

Compounds (2)