BMED 5207 polypetide chain elongation (exam 3)

first step of polypeptide chain elongation

eEF1a binds GTP and an aa-tRNA: a ternary complex is formed

second step of polypeptide chain elongation

the codon at the A site recruits the complementary aa-tRNA-eEF1a-FTP complex

third step of polypeptide chain elongation

correct codon-anticodon pairing induces hydrolysis of GTP by eEF1a; this leads to conformaiton change in the ribosome, and th eeEF1a is released

fourth step of polypeptide chain elongation

in the new conformation state of the ribosome, the two aa-tRNAs are close to each other and the large rRNA catalyzes the formation of the peptide bond using the energy stored in the ester bond of the aa-tRNA at the P site

fifth step of polypeptide chain elongation

the 80S complex binds eEF2-GTP. The GTP is hydrolyzed by EF2 and this provides the energy for translocation: the ribosome moves “forward” by 3 bases and tRNA ends up in the E site. Now, the dipeptidyl-tRNA is at the P site, the ribosome is ready to by the next ternary complex at the A site