Translation Flashcards
aminoacyl tRNA synthetase
Covalently link each amino acid to its correct tRNA (2 step mechanism).
What direction is a protein synthesized?
From N terminus to C terminus (adds to C terminus).
Small subunit
Provides frame work on which the tRNA are accurately matched to the codons of the mRNA.
Large subunit
Catalyzes the formation of the peptide bonds.
Where do the 2 subunits join together?
Near the 5’ end of mRNA.
Peptidyl transferase
Enzyme in the large subunit that catalyzes the peptide bond formation between the amino acid chain on the tRNA in the P site and the amino acid on the tRNA in the A site.
Bacterial ribosome
70S
Eukaryotic ribosome
80S
EF-Tu
Hydrolyzes GTP while trying to “swing” aminoacyl tRNA into the A site of the ribosome, it lets go when GTP is hydrolyzed.
What are the 2 elongation factors in bacteria?
EF-Tu and EF-G.
What are the 2 elongation factors in eukaryotes?
EF1 and EF2.
EF-G
Brings a GTP that hydrolyzes and provides the energy for the small subunit to move.
elF2
Bound to initiator tRNA when it binds to the small subunit.
What happens after met-tRNA binds to the small subunit?
mRNA with elF4E and elF4G bind at the 5’ end recognized by the cap.
What direction does the small subunit move?
5’ to 3’
What are the three stop codons?
UAA, UAG and UGA.
What does a release factor do?
Forces peptidyl transferase to catalyze an addiation of water instead of an amino acid.
What do upf proteins do?
Triggers mRNA degradation if there are still EJC’s on mRNA when a stop codon is recognized.
hsp70 and hsp60
Molecular chaperones that try to fix misfolded proteins by hydrolyzing ATP.
Proteosome
Destroys proteins with a polyubiquintin chain.
How is the ubiquitylation of a protein directed?
When the N terminal residue of a protein is acetylated, it is recognized by a specific E3 enzyme which directs it. If the protein is folded correctly, the acetlyated N terminus will be on the inside.
