Each mRNA in a cell can code for the primary amino acid sequence of a protein, using a triplet of nucleotides (codon) to represent each of the amino acids. Some amino acids are represented by more than one codon, because there are more triplet codons than there are amino acids. The codons in mRNA do not interact directly with the amino acids they specify. The translation of the individual codons of mRNA into protein depends on the presence of another RNA molecule, tRNA, which has a cloverleaf structure. On the top leaf of the tRNA structure, three nucleotides form a complementary codon (an anticodon) to each mRNA nucleotide triplet. Thus, each mRNA nucleotide triplet can code for a specific amino acid. Each tRNA carries an amino acid corresponding to its anticodon, and when thus "charged," the complex is termed aminoacyl-tRNA. Anticodons of aminoacyl-tRNA bind with mRNA codons in ribosomes. Ribosomes, a complex of rRNA and enzymes needed for translation, provide the structure on which tRNA can bind with the codons of mRNA in sequential order.

Initiation of protein synthesis involves the assembly of the components of the translation system. These components include the two ribosomal subunits, the mRNA to be translated, the aminoacyl-tRNA specified by the first codon in the message, guanosine triphosphate (GTP), and initiation factors that facilitate the assembly of this initiation complex. In eukaryotes, there are at least 12 distinct translation initiation factors (Roll-Mecak et al. 2000). After the ribosome recognizes the specific start site on the mRNA sequence, which is always the codon AUG coding for methionine, it slides along the mRNA molecule strand and translates the nucleotide sequence one codon at a time, adding amino acids to the growing end of the polypeptide chain (the elongation process). During elongation, the ribosome moves from the 5'-end to the 3'-end of the mRNA that is being translated. The binding of GTP to the elongation factor tu (EFtu) promotes the binding of aminoacyl-tRNA to the ribosome (Wieden et al. 2002). When the ribosome finds a stop codon (UAA, UGA, or UAG) in the message RNA, the mRNA, the tRNA, and the newly synthesized protein are released from the ribosomes, with the help of release factors that also bind GTP. The translation process is stopped, and a nascent protein exists.

It is noteworthy that initiation, elongation, and release factors undergo a conformational change upon the binding of GTP. In this regard, they are similar to the G proteins (both heterotrimeric G proteins and small "ras-like" G proteins) involved in cellular signaling (Halliday et al. 1984; Kaziro et al. 1991).

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