8 Questions
Which of the following is true about the methionine on the initiator tRNA in eukaryotes?
It is not formylated
Where does the initiation complex form in eukaryotic translation?
At the 5' terminus of the mRNA
What sequence does the initiation complex scan for in eukaryotic mRNA?
AUG initiation codon
What is the role of the eIF4E factor in eukaryotic translation initiation?
Binding to the 5' cap
Which components interact indirectly during the initiation of eukaryotic translation?
Ribosome and mRNA
What happens to ATP during the initiation of eukaryotic translation?
It is converted to ADP
Which subunit binds to the initiation factors eIF1, eIF1A, eIF3, and eIF5?
40S subunit
What describes the Kozak consensus sequence?
The most conserved bases around the AUG start codon from all human mRNAs
Study Notes
Translation Initiation in Eukaryotes
- The initiator tRNA has an amino group of methionine that is not formylated, meaning it's Met instead of fMet.
- The initiation complex forms at the 5' terminus of the mRNA.
- There is no Shine-Dalgarno-AUG start sequence, and the initiation complex scans the mRNA for an AUG initiation codon.
- Translation usually begins at the first AUG found.
Kozak Consensus Sequence
- The Kozak Consensus Sequence is a sequence logo that shows the most conserved bases around the AUG start codon from all human mRNAs.
- The consensus sequence is ACCAUGG.
Stage 2: Initiation in Eukaryotes
- The 40S subunit binds to initiation factors eIF1, 1A, 3, and 5 to prepare the ribosome.
- tRNA-Met binds to eIF2-GTP to prepare the first amino acid.
- eIF4 family and PolyA Binding Protein (PABP) check the ends of the mRNA to prepare the RNA.
- ATP is hydrolyzed to ADP, releasing all factors, and the 60S subunit binds.
- The ribosome (40S subunit) and mRNA interact indirectly, with both ends of the mRNA bound.
- The eIF4F complex, containing eIFs 4E, G, and A, binds to the 5' CAP.
- eIF4E binds to the 5' cap, while PAB binds to the 3' poly(A) tail.
- eIF4G binds to both PAB and eIF4E, and eIF3 binds to the 40S subunit and the initiation complex.
Understand the process of translation initiation in eukaryotes, including the role of initiator tRNA, the initiation complex, and the Kozak Consensus Sequence.
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