Quiz 3.2 Flashcards
Translation components in eukaryotes
mRNA with codons including AUG, tRNA with amino acids and anticodons to compliment, Translation factors
Eukaryotic translation factors
eIFs are eukaryotic Initiation factors, eEFs are elongation factors, eRFs are release factors
Initiation of translation euk.
Starts with nuclear export of mRNA, where cap and tails’ proteins bind to NES nuclear export signals, allowing exportin to bind to export it. mRNA binds to eIF4E in cytoplasm and tRNA with Met binds to eIFII. Small ribosomalsubunit binds to eIF1, 3, and 5. All eIFs bind together to ASS. Components slide down to the start codon AUG, where eIFs are released and the large ribosomal unit attaches, 1st tRNA at the P site. 2nd tRNA enters the A site escorted by eEF1a.
Elongation of translation euk.
1st tRNA with Methionine is attached at its C terminal to the N terminal of the amino acid of the next tRNA using peptidyl transferase. Ribosome slides over one codon on the mRNA using eEFII. tRNAs without amino acids exit in the E site, polypeptide is made by assembling amino acids with peptidyl transferase.
Termination of translation euk.
Tln continues until a stop codon UGA, UAG, or UAA enters the A site. No tRNA compliments the stop codon, eRFI enters the A site, releasing the polypeptide and disassembling the Tln complex, releasing mRNA, tRNA, ribosome.
Order of eIFs
eIF4E to mRNA and eIF2 to tRNA, eIF1 + 3 + 5 to ribosome, start codon reached eIFs dissasemble
Peptidyl transferase
forms peptide bonds between the C terminal of the P site amino acid and the N terminal of the A site amino acid
eEF1a
escorts tRNA into the A site during elongation
eEF2
slides the ribosome down a codon in Tln
eRF1
binds to stop codon, releasing amino acid and translation components
Regulation of Translation methods
Can regulate the cap and tail of mRNA to change stability. Regulate translation factors, mRNA stability, mRNA nuclear export, and polysome/amount of ribosomes on a strand of mRNA.
