Translocation

Translocation

Translocation - The movement of the ribosome relative to mRNA is called translocation. During translocation the ribosome moves along the mRNA strand, a codon at a time, from the initiation site at or near the 5' end of mRNA to the termination codon near the 3' end.

The movement of the ribosome relative to mRNA is in the 5'-->3' direction.During the first translocation movement, the aa₂tRNA complex, with attached methionine / N-formylmethionine, shifts from the A 4 site to the P site. The A site therefore becomes vacant and is now occupied by the third amino acid tRNA complex (aa₃tRNA).

This process is repeated, and elongation of the polypeptide chain is thus brought about by step by step addition of amino acidsIn prokaryotes, translocation is brought by elongation factor G (EF-G) or translocase. EF-G consists of a single polypeptide chain with a molecular weight of 72,000.84.000. EP-G rapidly hydrolyzes GTP to GDP+Pi in the presence of ribosomes.

In this reaction the 30S subunit is inactive. The 50S subunit can only partially support the reaction. However, if 308 subunits are added to 50S subunits hydrolysis is similar to that of 70S ribosomes. Till recently it was believed that the energy released during hydrolysis of GTP was utilized for translocation and unloading of deacylated tRNA from the P site. Recent studies have. however, shown that hydrolysis is not coupled with translocation.

	Back to Home
Protein Synthesis Part 1 Release of Deacylated tRNA Hydrolysis of GTP Locking and Unlocking Ribosome Model inchworn Theory Conformational Changes Recognition of the Termination Signal Release of the Polypeptide Chain Prokaryote and Eukaryote Release Factors Processing Polypeptide Chain Rate of Protein Synthesis Signal Hypothesis Prokaryote and Eukaryote Protein Synthesis Teminism

Home | Site map | Submit Article | Resources | Search