Molecular biologyLesson 4 of 5 in the course Gene Expression

Eukaryotic Translation Initiation and Protein-Level Regulation

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

After RNA reaches the cytoplasm, it can be translated into protein. Cells regulate this process by controlling how efficiently translation begins and how long RNA and proteins remain available or active. This lesson explains how the eukaryotic translation initiation complex forms, how chemical modifications regulate protein activity and location, and how ubiquitin marks proteins for degradation.

All flashcards

What does eIF-2 do during eukaryotic translation initiation?
Bound to GTP, eIF-2 carries the initiating Met-tRNAi to the 40S ribosomal subunit.
Why does eIF-2 phosphorylation impede translation?
It changes eIF-2's shape so it cannot bind GTP, disrupting initiation-complex assembly.
How can chemical modifications affect proteins?
They can change protein activity, location, interactions, or how long the protein persists.
What are the roles of ubiquitin and the proteasome?
Ubiquitin can tag a protein for degradation; the proteasome degrades tagged proteins.
How can mRNA stability affect protein production?
An mRNA that persists longer in the cytoplasm remains available for translation longer.

Quiz questions

  1. What role does eIF4F play in eukaryotic translation initiation?Answer: It helps bring the mRNA-associated complex together with the 40S ribosomal complex.
  2. What happens after the initiator tRNA anticodon aligns with the AUG start codon?Answer: GTP is hydrolyzed, initiation factors are released, and the 60S subunit joins.
  3. How do interactions involving the mRNA's 5′ cap and poly-A tail help translation initiation?Answer: They bring the mRNA's ends close together, forming a loop.
  4. Which effect can a chemical modification have on a protein?Answer: It can alter the protein's activity, location, or interactions with other molecules.
  5. How can phosphorylation of eIF-2 affect translation initiation?Answer: It prevents eIF-2 from binding GTP, impeding initiation-complex formation.

Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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