Ef-G

Definition

ef-G is a translation factor in prokaryotic protein synthesis that plays a vital role in the translocation step of translation. It aids in the movement of the ribosome along the messenger RNA (mRNA) after peptide bond formation, ensuring that the ribosome shifts properly to read the next codon. This factor is essential for maintaining the accuracy and efficiency of protein synthesis by facilitating the elongation process in ribosomes.

5 Must Know Facts For Your Next Test

1. ef-G is a GTP-binding protein, which means it hydrolyzes GTP to GDP and inorganic phosphate to provide energy for the translocation process.
2. The action of ef-G promotes the release of deacylated tRNA from the ribosome after the peptide bond has formed.
3. ef-G binds to the ribosome in a conformation that facilitates the movement of tRNA and mRNA, ensuring accurate reading of the genetic code.
4. Inhibition or dysfunction of ef-G can lead to stalled ribosomes, which can disrupt protein synthesis and have significant cellular consequences.
5. This factor is particularly important in bacteria, where it ensures rapid and efficient translation, crucial for their survival and growth.

Review Questions

• How does ef-G contribute to the accuracy of protein synthesis during translation?
  • ef-G enhances the accuracy of protein synthesis by facilitating translocation, which is when the ribosome moves along the mRNA strand after each amino acid addition. This movement ensures that the next codon is correctly positioned at the ribosomal active site, allowing for proper tRNA binding. Without ef-G, ribosomes may stall or misread codons, leading to errors in protein synthesis.
• Discuss the mechanisms by which ef-G interacts with the ribosome during translation elongation.
  • During translation elongation, ef-G interacts with the ribosome in a GTP-bound state. Once bound, ef-G undergoes a conformational change that allows it to promote translocation by positioning itself at the ribosome's A-site. The hydrolysis of GTP to GDP then drives the movement of tRNA from the A-site to the P-site, facilitating efficient progression through the elongation cycle. This interaction is crucial for maintaining smooth and rapid translation.
• Evaluate the potential impacts on cellular function if ef-G were inhibited or malfunctioned.
  • If ef-G were inhibited or malfunctioned, it would lead to stalled ribosomes unable to properly translocate along mRNA during protein synthesis. This disruption could cause accumulation of incomplete polypeptides and stress on cellular machinery, potentially triggering stress responses or cell death. The inability to synthesize proteins efficiently would severely impact cellular functions, growth, and overall organism viability, especially in bacteria where rapid protein synthesis is critical for survival.

Related terms

Ribosome: A molecular machine made up of ribosomal RNA (rRNA) and proteins that synthesizes proteins by translating mRNA into polypeptide chains.

Translocation: The process during protein synthesis where the ribosome moves along the mRNA strand, shifting its position to read the next codon after each amino acid is added to the growing polypeptide chain.

Peptidyl transferase: An enzymatic activity of the ribosome responsible for forming peptide bonds between amino acids during protein synthesis.