Elongation factor

Elongation Factor

Elongation Factor Tu bound to GDP

Elongation factors are a set of proteins that play a crucial role in the process of protein synthesis by facilitating the elongation phase of translation. These factors are essential for the accurate and efficient addition of amino acids to the growing polypeptide chain during ribosomal translation of mRNA.

Types of Elongation Factors

There are several types of elongation factors, each with specific functions in the translation process. The most well-known elongation factors include:

Elongation Factor Tu (EF-Tu)

Elongation Factor Tu (EF-Tu) is a GTP-binding protein that plays a key role in the delivery of aminoacyl-tRNA to the A site of the ribosome. EF-Tu binds to aminoacyl-tRNA in a GTP-dependent manner and escorts it to the ribosome. Upon correct codon-anticodon pairing, GTP is hydrolyzed, and EF-Tu is released, allowing the aminoacyl-tRNA to participate in peptide bond formation.

Elongation Factor G (EF-G)

Elongation Factor G (EF-G) is involved in the translocation step of translation. After peptide bond formation, EF-G binds to the ribosome and facilitates the movement of tRNA and mRNA through the ribosome, allowing the next codon to be positioned in the A site. This process is also GTP-dependent.

Elongation Factor Ts (EF-Ts)

Elongation Factor Ts (EF-Ts) acts as a guanine nucleotide exchange factor for EF-Tu. It catalyzes the release of GDP from EF-Tu, allowing GTP to bind and reactivate EF-Tu for another round of aminoacyl-tRNA delivery.

Function in Translation

During the elongation phase of translation, elongation factors ensure the correct and efficient addition of amino acids to the growing polypeptide chain. The process involves several steps:

1. Aminoacyl-tRNA Binding: EF-Tu delivers the correct aminoacyl-tRNA to the A site of the ribosome.
2. Peptide Bond Formation: The ribosome catalyzes the formation of a peptide bond between the amino acid in the A site and the growing polypeptide chain in the P site.
3. Translocation: EF-G facilitates the movement of tRNA and mRNA, shifting the ribosome along the mRNA to position the next codon in the A site.

Importance in Cellular Function

Elongation factors are vital for cellular function as they ensure the fidelity and efficiency of protein synthesis. Errors in translation can lead to the production of malfunctioning proteins, which can have deleterious effects on cell function and viability.

Related Pages

• Translation (biology)
• Ribosome
• Protein synthesis
• Aminoacyl-tRNA