Process of protein biosynthesis
Fig. 8.16 Translation process of protein synthesis in prokaryotes.
Initiation of protein synthesis requires assembly of the ribosomal subunits, messenger RNA, and initiator tRNA at the start codon. This organization of translational components is facilitated by protein initiation factors (Fig. 5). FIGURE 5 Translation initiation. In prokaryotes, three initiation factors are responsible for assembling the initiation complex prior to decoding of a message. The […]
Components of Protein Synthesis
The heart of protein biosynthesis lies in the elongation cycle, with its sequential decoding of mRNA codons to assemble the useful portion of the polypeptide. Elongation can be further broken down into three phases— aminoacyl-tRNA decoding, peptide bond formation, and translocation of the new peptidyl-tRNA (Fig. 7). A. Decoding According to Base Pairing Comparison of […]
Procedure of Protein Synthesis - Web Books
One of three mRNA codons - UAA, UAG and UGA - is used to signal to the elongating ribosome that translation should be terminated at this point. Upon the arrival of the stop codon at the ribosomal acceptor(A)-site, a protein release factor (RF) binds to the ribosome resulting in the peptidyl transferase centre of the ribosome switching to a hydrolytic function to remove the completed polypeptide chain from the peptidyl-tRNA bound at the adjacent ribosomal peptidyl(P)-site. In this review recent advances in our understanding of the mechanism of termination in the bacterium Escherichia coil will be summarised, paying particular attention to the roles of 16S ribosomal RNA and the release factors RF-1, RF-2 and RF-3 in stop codon recognition. Our understanding of the translation termination process in eukaryotes is much more rudimentary with the identity of the single eukaryotic release factor (eRF) still remaining elusive. Finally, several examples of how the termination mechanism can be subverted either to expand the genetic code (e.g. selenocysteine insertion at UGA codons) or to regulate the expression of mammalian retroviral or plant viral genomes will be discussed.
What are the basic steps of protein synthesis? | Chemistry
Following release of the synthesized protein, the ribo-some contains an empty tRNA in the P-site or E-site, and mRNA is still bound with the stop codon in the A-site. This arrangement of components is the post-termination complex. A protein known as the ribosome recycling factor (RRF) promotes the dissociation of this complex in preparation for […]