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RNA splicing is a fundamental aspect of post transcriptional control. After an RNA molecule is transcribed from DNA, it contains both exons (coding regions) and introns (non-coding regions). Introns need to be removed for the RNA to be functionally active. This removal process is known as RNA splicing. In RNA splicing, introns are cut out, and exons are joined together to form a mature mRNA molecule ready for translation.

The splicing process is carried out by a complex known as the spliceosome. The spliceosome is composed of small nuclear RNAs (snRNAs) and a host of associated proteins. This machinery ensures that splicing is performed with high precision, ensuring that no exonic regions are lost, and the introns are fully excised.

RNA splicing allows for alternative splicing, where a single gene can produce multiple proteins. This dramatically increases protein diversity without the need for additional genes.

• Introns: Non-coding sequences
• Exons: Coding sequences
• Spliceosome: Complex responsible for RNA splicing
• Alternative splicing: One gene, multiple proteins

RNA shuttling, also known as RNA transport, is another crucial element of post-transcriptional control. Once the mRNA is fully processed, it needs to be transported from the nucleus to the cytoplasm, where protein synthesis occurs.

During this process, the mature mRNA exits the nucleus through nuclear pores, complex structures embedded in the nuclear membrane. Various proteins aid in this transport process, ensuring that mRNA molecules are efficiently and safely shuttled to the cytoplasm.

This transportation is not only vital for mRNA but also for other RNA types such as tRNAs and rRNAs. It ensures that these RNAs are available at the right time and place for protein synthesis or other cellular functions.

• Nuclear pores: Pathways for RNA transport
• tRNA: Transfer RNA
• rRNA: Ribosomal RNA

RNA stability controls how long an RNA molecule remains intact within a cell, thus influencing its availability for protein synthesis. The stability of an RNA molecule determines its half-life—the time it takes for half of the RNA molecules to degrade.

Several factors influence RNA stability, including RNA binding proteins, sequence elements within the RNA, and exonucleases that degrade RNA. For instance, the presence of certain sequence motifs can make an RNA molecule more susceptible to degradation.

RNA stability is a tightly regulated process as it ensures that proteins are synthesized as needed and prevents unnecessary protein production. Mechanisms like deadenylation (removal of the poly-A tail) and decapping (removal of the 5' cap) are critical in regulating RNA degradation.

• Half-life: Duration an RNA stays intact
• RNA binding proteins: Influence RNA stability
• Exonucleases: Enzymes degrading RNA
• Deadenylation: Removal of poly-A tail
• Decapping: Removal of 5' cap