Fig. 2.

mRNA translation can by divided into three steps: initiation, elongation and termination. The translation of mRNA into protein begins with initiation. In cap-dependent initiation, the eukaryotic initiation factors (eIFs) bind to the mRNA cap and recruit the 43S pre-initiation complex. This complex then scans the mRNA in a 5′ to 3′ direction until it encounters a start codon (AUG). The 60S subunit is subsequently recruited to form an 80S monosome, which carries out translation elongation. Ribosomes, together with charged tRNAs, decode successive codons and catalyze peptide bond formation. The differential phosphorylation of eEF2 can change the rate of elongation. Termination occurs when the ribosome encounters a stop codon. Stop codon readthrough often occurs in a transcript and cell type-specific manner, resulting in the formation of longer polypeptides.