3' untranslated region (3' UTR)

Definition

The 3' untranslated region (3' UTR) is a segment of messenger RNA (mRNA) that follows the coding sequence and is not translated into protein. This region plays a crucial role in the regulation of gene expression by influencing mRNA stability, localization, and translation efficiency. The 3' UTR contains various regulatory elements that can interact with proteins and microRNAs, ultimately affecting the fate of the mRNA within the cell.

5 Must Know Facts For Your Next Test

1. The 3' UTR can contain binding sites for regulatory proteins that stabilize the mRNA or mark it for degradation.
2. Alternative polyadenylation can lead to different lengths of 3' UTRs, which may affect how the mRNA is regulated and expressed in different tissues.
3. MicroRNAs that bind to the 3' UTR can downregulate gene expression by preventing translation or promoting degradation of the mRNA.
4. Changes or mutations in the 3' UTR can impact the regulation of genes and are associated with various diseases, including cancer.
5. The presence of specific motifs within the 3' UTR can determine how effectively an mRNA is translated into protein, influencing cellular responses to environmental signals.

Review Questions

• How does the 3' untranslated region (3' UTR) influence mRNA stability and gene expression?
  • The 3' UTR plays a vital role in regulating mRNA stability and gene expression by containing sequences that bind to proteins and other RNA molecules. These interactions can either stabilize the mRNA, allowing for prolonged translation, or promote its degradation. By influencing how long an mRNA remains functional in the cell, the 3' UTR effectively modulates how much protein is produced from a given gene.
• Discuss the relationship between microRNAs and the 3' UTR in post-transcriptional regulation.
  • MicroRNAs are key players in post-transcriptional regulation and often target specific sequences within the 3' UTR of mRNAs. When a microRNA binds to its complementary site in the 3' UTR, it can lead to either degradation of the mRNA or repression of its translation into protein. This relationship highlights how microRNAs fine-tune gene expression by controlling which proteins are synthesized based on cellular needs.
• Evaluate how alternative polyadenylation affects gene regulation through changes in the 3' UTR length.
  • Alternative polyadenylation results in different lengths of 3' UTRs, which can significantly alter gene regulation. Longer 3' UTRs may contain additional regulatory elements that provide more opportunities for binding by regulatory proteins or microRNAs. This can lead to differential stability or translation efficiency of the mRNAs, allowing cells to adapt their protein synthesis based on developmental stages or environmental cues. Understanding this mechanism provides insights into how alterations in these processes may contribute to diseases such as cancer.

Related terms

Polyadenylation: The addition of a poly(A) tail to the 3' end of an mRNA molecule, which enhances mRNA stability and aids in its export from the nucleus.

MicroRNA: Small, non-coding RNA molecules that regulate gene expression by binding to complementary sequences in mRNA, often in the 3' UTR, leading to degradation or inhibition of translation.

mRNA stability:

The lifespan of an mRNA molecule within the cell, influenced by sequences and structures present in the 5' and 3' UTRs, as well as interactions with proteins and RNAs.