ZOOHCC - 501: Molecular Biology (Theory)
Unit 4: Translation
Proteins involved in translation
Translation is the process by which genetic information in mRNA is used to synthesize a protein. It involves the coordination of many different proteins and RNA molecules. The proteins involved in translation can be broadly classified into three categories based on the stages of translation: initiation, elongation, and termination.
Initiation factors: Proteins called initiation factors are involved in the assembly of the ribosome on the mRNA and the selection of the correct start codon. These include:
IF1, IF2, and IF3: These proteins help to assemble the ribosome on the mRNA and stabilize the correct start codon in the ribosome's P-site.
eIF1, eIF2, eIF3, and eIF4: These proteins are involved in the initiation of translation in eukaryotes.
Elongation factors: Elongation factors help to add amino acids one by one to the growing polypeptide chain. These include:
EF-Tu and EF-Ts: These proteins help to bring aminoacyl-tRNAs to the ribosome and ensure that the correct amino acid is added to the growing polypeptide chain.
EF-G: This protein helps to translocate the ribosome along the mRNA.
Termination factors: Termination factors are involved in the recognition of stop codons and the release of the polypeptide chain from the ribosome. These include:
RF1 and RF2: These proteins recognize stop codons and trigger the release of the polypeptide chain from the ribosome.
eRF1: This protein is the eukaryotic equivalent of RF1 and RF2.
Explanation
Proteins involved in the three stages of protein synthesis, initiation, elongation, and termination, are as follows:
Initiation:
The process of translation starts with the initiation stage where the ribosome assembles on the mRNA and selects the correct start codon. The following proteins are involved in the initiation stage:
Initiation factors (IFs): IF1, IF2, and IF3 are proteins that help to assemble the ribosome on the mRNA and stabilize the correct start codon in the ribosome's P-site.
Small ribosomal subunit: This subunit of the ribosome binds to the mRNA and scans for the start codon.
Elongation:
Once the ribosome has identified the start codon, the elongation stage begins, where amino acids are added one by one to the growing polypeptide chain. The following proteins are involved in the elongation stage:
Elongation factors (EFs): EF-Tu and EF-Ts are proteins that help to bring aminoacyl-tRNAs to the ribosome and ensure that the correct amino acid is added to the growing polypeptide chain.
Large ribosomal subunit: This subunit of the ribosome catalyzes the formation of peptide bonds between amino acids.
Termination:
The termination stage occurs when the ribosome reaches a stop codon on the mRNA, and the newly synthesized polypeptide chain is released. The following proteins are involved in the termination stage:
Release factors (RFs): RF1 and RF2 are proteins that recognize stop codons and trigger the release of the polypeptide chain from the ribosome.
Ribosome recycling factor (RRF): RRF helps to dissociate the ribosome from the mRNA and recycle its subunits for the next round of translation.
Overall, protein synthesis is a complex process that involves the coordinated action of many proteins and RNA molecules.
