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Translation is one of the key energy consumers in cells, hence it is strictly regulated. Numerous mechanisms have evolved that control and regulate translation in eukaryotes as well as prokaryotes. Regulation of translation can impact the global rate of protein synthesis which is closely coupled to the metabolic and proliferative state of a cell.
Overview of eukaryotic messenger RNA (mRNA) translation Translation of mRNA and ribosomal protein synthesis Initiation and elongation stages of translation involving RNA nucleobases, the ribosome, transfer RNA, and amino acids The three phases of translation: (1) in initiation, the small ribosomal subunit binds to the RNA strand and the initiator tRNA–amino acid complex binds to the start ...
The ribosomal P-site plays a vital role in all phases of translation. Initiation involves recognition of the start codon (AUG) by initiator tRNA in the P-site, elongation involves passage of many elongator tRNAs through the P site, termination involves hydrolysis of the mature polypeptide from tRNA bound to the P-site, and ribosome recycling involves release of deacylated tRNA.
Targeting the rate-limiting initial step is the most efficient in terms of energy costs for the cell. Transcription initiation is regulated by cis-acting elements (enhancers, silencers, isolators) within the regulatory regions of the DNA, and sequence-specific trans-acting factors that act as activators or repressors. [1]
Elongation is the most rapid step in translation. [3] In bacteria , it proceeds at a rate of 15 to 20 amino acids added per second (about 45-60 nucleotides per second). [ citation needed ] In eukaryotes the rate is about two amino acids per second (about 6 nucleotides read per second).
The rate of DNA replication in a living cell was first measured as the rate of phage T4 DNA elongation in phage-infected E. coli. [18] During the period of exponential DNA increase at 37 °C, the rate was 749 nucleotides per second. The mutation rate per base pair per replication during phage T4 DNA synthesis is 1.7 per 10 8. [19]
EF-G (elongation factor G, historically known as translocase) is a prokaryotic elongation factor involved in mRNA translation. As a GTPase , EF-G catalyzes the movement (translocation) of transfer RNA (tRNA) and messenger RNA (mRNA) through the ribosome .
In the context of translation, a termination signal is the stop codon on the mRNA that elicits the release of the growing peptide from the ribosome. [2] Termination signals play an important role in regulating gene expression since they mark the end of a gene transcript and determine which DNA sequences are expressed in the cell. [1]