Translation Flashcards
Semester 1 year 1
What occurs in the small and large subunits of a ribosome?
-small - where codon/anticodon binding occurs
-large - where peptide bond formation occurs
What is found at the subunit interface?
3 non-overlapping tRNA binding sites (A,P,E)
-binds to A site first, then moves to P site, then E site before being released
Where does ribosome synthesis occur?
-rRNA transcription + early rRNA processing occurs in nucleoli
-later processing + assembly occurs in nucleoplasm + cytoplasm
What does translation elongation involve?
-aminoacyl-tRNA binding
-peptide bond formation
-translocation of ribosome along mRNA
What is the role of GTPases in translation elongation?
-aminoacyl-tRNA is brought to the ribosome by an elongation factor EF1A
-translation requires another elongation factor EF2
-EF1A and EF2 are GTPases
-2 GTP molecules are hydrolysed per elongation cycle
What are the elongation factors called in prokaryotes?
-EF1A is EF-Tu in prokaryotes
-EF2 is EFG in prokaryotes
How is translation initiated in eukaryotes?
-initiator tRNA^Met is bound to EIF2, and together with the small subunit is assembled at the 5’ end of mRNA due to interaction with the cap-binding complex
-preinitiation complex scans along the mRNA until it finds an AUG codon in an appropriate sequence context
-after selection of start codon, large subunit is recruited
How is translation terminated in eukaryotes?
-stop codons are recognised by protein termination factors
-2 release factors act together
-initial binding of eukaryotic release factor 1 (eRF1) triggers peptide hydrolysis
-eRF3 allows release of RF1/RF2 from ribosome
What are the GTPases involved in translation?
-EF1A
-EF2
-eIF2
-eRF3
How does translation termination occur on prokaryotes?
Same as in eukaryotes, except peptide hydrolysis is triggered by RF1/RF2 and RF3 allows RF1/RF2 release from ribosomes
