What is the translation initiation complex?
Table of Contents
What is the translation initiation complex?
Translation initiation is a complex process in which initiator tRNA, 40S, and 60S ribosomal subunits are assembled by eukaryotic initiation factors (eIFs) into an 80S ribosome at the initiation codon of mRNA.
What happens in elongation of translation?
During the elongation stage, the ribosome continues to translate each codon in turn. Each corresponding amino acid is added to the growing chain and linked via a bond called a peptide bond. Elongation continues until all of the codons are read.
What is the function of initiation factor 3?
We provide evidence that translation initiation factor 3 (IF3), an essential component of the prokaryotic translation initiation machinery that binds the 30S subunit and blocks premature association with the 50S subunit, is part of the control of green light induction pathway.
What is the key role that eIF2B plays in translation?
eIF2B is critical for regulation of protein synthesis via a conserved mechanism of phosphorylation of eIF2, which converts eIF2 from a substrate to an inhibitor of eIF2B GEF.
What is the purpose of elongation?
Translation elongation factors perform critical functions in protein synthesis in all domains of life, including the delivery of aminoacyl-tRNAs into the ribosome, and the translocation of peptidyl-tRNA from the ribosomal A-site to the ribosomal P-site.
How does phosphorylation regulate translation initiation in eukaryotes?
A central mechanism for translational control involves phosphorylation of the α subunit of eukaryotic initiation factor (eIF) 2 (eIF2α~P),3 which represses the initiation phase of protein synthesis, allowing cells to conserve resources while a new gene expression program is adopted to prevent stress damage.
How GTP is involved in the functional activity of eIF2?
GTP is hydrolyzed to release eIF2 from the ribosome in the GDP-bound state. Exchange of GDP for GTP on eIF2 is catalyzed by a five-subunit factor termed eIF2B and is required to reconstitute a functional ternary complex for a new round of translation initiation (Hinnebusch, 2000).
What is the function of initiation factor 1?
Bacterial initiation factor 1 is a bacterial initiation factor. IF1 associates with the 30S ribosomal subunit in the A site and prevents an aminoacyl-tRNA from entering. It modulates IF2 binding to the ribosome by increasing its affinity.
What are initiation factors in transcription?
Transcription initiation factors (TFII) are proteins which enable RNA polymerase II to bind to the DNA template in order to start the transcription process. TFIIA is one of several TFs which are required for transcription.
Where does translation initiation occur?
the ribosome
Initiation of translation occurs when mRNA, tRNA, and an amino acid meet up inside the ribosome. Once translation has begun, it continues down the line as mRNA shifts along through the ribosome. Each new codon matches with a new tRNA anticodon, bringing in a new amino acid to lengthen the chain.
What signals the beginning of translation?
At the beginning of translation, the ribosome and a tRNA attach to the mRNA. The tRNA is located in the ribosome’s first docking site. This tRNA’s anticodon is complementary to the mRNA’s initiation codon, where translation starts. The tRNA carries the amino acid that corresponds to that codon.
What is role of eIF2 in protein synthesis after it is activated by eIF2B?
eIF2 binds initiator tRNA to ribosomes and promotes mRNA AUG codon recognition. eIF2B is critical for regulation of protein synthesis via a conserved mechanism of phosphorylation of eIF2, which converts eIF2 from a substrate to an inhibitor of eIF2B GEF.
How many initiation factors do eukaryotes have during translation of protein?
eleven different initiation factors
In eukaryotes, at least eleven different initiation factors are required to properly initiate translation. Collectively, they ensure that the methionyl-initiator tRNA (Met-tRNAiMet) is brought in the P site of the ribosome to the initiator AUG of an mRNA.
