key term - Polyadenylation

Definition

Polyadenylation is the process of adding a poly(A) tail, a long sequence of adenine nucleotides, to the 3' end of a messenger RNA (mRNA) molecule. This post-transcriptional modification is essential for the stability, localization, and translation of mRNA in eukaryotic cells.

5 Must Know Facts For Your Next Test

1. The poly(A) tail helps protect the mRNA from degradation by exonucleases, increasing its stability and lifespan within the cell.
2. The poly(A) tail also facilitates the export of mRNA from the nucleus to the cytoplasm, where it can be translated into proteins.
3. Polyadenylation is catalyzed by a multi-subunit enzyme complex called the polyadenylation machinery, which recognizes specific sequences in the mRNA.
4. The length of the poly(A) tail can vary, with longer tails generally associated with more stable mRNAs and higher translation efficiency.
5. Disruption of the polyadenylation process can lead to various diseases, including cancer, neurological disorders, and cardiovascular diseases.

Review Questions

• Explain the role of polyadenylation in the regulation of mRNA stability and translation.
  • Polyadenylation plays a crucial role in the regulation of mRNA stability and translation in eukaryotic cells. The addition of a poly(A) tail to the 3' end of the mRNA molecule protects it from degradation by exonucleases, increasing its lifespan within the cell. This enhanced stability allows the mRNA to be more efficiently exported from the nucleus and transported to the ribosomes for translation into proteins. Additionally, the poly(A) tail interacts with the 5' cap of the mRNA, forming a closed loop that facilitates the recruitment of translation initiation factors, thereby enhancing the translation efficiency of the mRNA.
• Describe the process of polyadenylation and the key components involved.
  • Polyadenylation is a post-transcriptional modification that occurs in the nucleus of eukaryotic cells. It is catalyzed by a multi-subunit enzyme complex called the polyadenylation machinery, which recognizes specific sequences within the mRNA molecule, typically the AAUAAA hexamer. The polyadenylation machinery then adds a long sequence of adenine nucleotides, known as the poly(A) tail, to the 3' end of the mRNA. This process is essential for the stability, localization, and translation of the mRNA, as the poly(A) tail protects the mRNA from degradation and facilitates its export from the nucleus and recruitment of translation initiation factors.
• Analyze the potential consequences of disruptions in the polyadenylation process and their implications for human health.
  • Disruptions in the polyadenylation process can have significant consequences for human health. Improper polyadenylation can lead to the production of mRNAs with altered stability, localization, or translation efficiency, which can contribute to the development of various diseases. For example, defects in the polyadenylation machinery or the recognition of polyadenylation signals have been linked to cancer, as they can result in the production of mRNAs with abnormal stability or translation, leading to the dysregulation of gene expression and cellular processes. Additionally, polyadenylation defects have been associated with neurological disorders, such as Alzheimer's disease, and cardiovascular diseases, highlighting the critical importance of this post-transcriptional modification in maintaining cellular homeostasis and overall human health.

Related terms

Transcription:

The process of synthesizing a complementary RNA molecule from a DNA template, which is the first step in gene expression.

mRNA:

Messenger RNA, which carries the genetic instructions from the nucleus to the ribosomes for protein synthesis.

Eukaryotic:

Organisms whose cells contain a nucleus and other membrane-bound organelles, including plants, animals, and fungi.