key term - Translational repression

Definition

Translational repression is a regulatory mechanism that prevents the translation of messenger RNA (mRNA) into proteins, effectively controlling gene expression at the translational level. This process can be initiated by various factors such as small regulatory RNAs, proteins that bind to mRNA, or other mechanisms that interfere with the ribosome's ability to translate the mRNA into a protein. Understanding translational repression is crucial because it allows cells to fine-tune protein synthesis in response to environmental changes and developmental cues.

5 Must Know Facts For Your Next Test

1. Translational repression can occur through various mechanisms, such as binding of regulatory proteins to the mRNA or interaction with small non-coding RNAs.
2. This process is vital for cellular responses to stress, as it allows for rapid downregulation of protein synthesis when resources are limited.
3. Translational repression can also play a role in developmental processes, where specific proteins need to be produced at particular stages.
4. Some viruses exploit translational repression to evade host defenses, shutting down host protein synthesis while synthesizing their own proteins.
5. Phosphorylation of translation initiation factors is one way that cells can modulate translational repression in response to signaling pathways.

Review Questions

• How does translational repression contribute to the regulation of gene expression?
  • Translational repression directly influences gene expression by inhibiting the translation of mRNA into protein. By preventing certain mRNAs from being translated, cells can control the levels of specific proteins without altering transcription rates. This mechanism allows for rapid adjustments in protein synthesis, which is especially important during times of stress or when adapting to changes in the environment.
• Discuss how small regulatory RNAs can mediate translational repression and give an example.
  • Small regulatory RNAs, such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), can mediate translational repression by binding to complementary sequences on target mRNAs. This binding can lead to either degradation of the mRNA or inhibition of translation by preventing ribosome assembly. For example, miRNAs can bind to the 3' untranslated regions (UTRs) of mRNAs, leading to reduced translation efficiency and therefore controlling protein levels post-transcriptionally.
• Evaluate the implications of translational repression in cellular responses to environmental changes and its potential impact on diseases.
  • Translational repression plays a critical role in how cells respond to environmental stressors such as nutrient deprivation or temperature changes by rapidly adjusting protein synthesis. This adaptability is crucial for maintaining cellular homeostasis and survival. However, dysregulation of this process can contribute to diseases such as cancer, where inappropriate translation of certain proteins may promote uncontrolled cell growth. Understanding these mechanisms provides insight into potential therapeutic targets for diseases linked to aberrant gene expression regulation.

Related terms

mRNA:

Messenger RNA is a type of RNA that conveys genetic information from DNA to the ribosome, where proteins are synthesized.

Ribosome: A ribosome is a molecular machine in the cell that facilitates the translation of mRNA into proteins by linking amino acids together.

Small interfering RNA (siRNA): Small interfering RNA is a class of double-stranded RNA molecules that play a role in the RNA interference pathway, leading to the degradation of specific mRNA.