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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.
In prokaryotes (bacteria and archaea), translation occurs in the cytosol, where the large and small subunits of the ribosome bind to the mRNA. In eukaryotes, translation occurs in the cytoplasm or across the membrane of the endoplasmic reticulum through a process called co-translational translocation.
Most common elongation factors in prokaryotes are EF-Tu, EF-Ts, EF-G. [1] Bacteria and eukaryotes use elongation factors that are largely homologous to each other, but with distinct structures and different research nomenclatures. [2] Elongation is the most rapid step in translation. [3]
Eukaryotic ribosomes are known to bind to transcripts in a mechanism unlike the one involving the 5' cap, at a sequence called the internal ribosome entry site. This process is not dependent on the full set of translation initiation factors (although this depends on the specific IRES) and is commonly found in the translation of viral mRNA. [9]
Another difference between eukaryotes and prokaryotes is mRNA transport. Because eukaryotic transcription and translation is compartmentally separated, eukaryotic mRNAs must be exported from the nucleus to the cytoplasm—a process that may be regulated by different signaling pathways. [6]
Bacterial transcription differs from eukaryotic transcription in several ways. In bacteria, transcription and translation can occur simultaneously in the cytoplasm of the cell, whereas in eukaryotes transcription occurs in the nucleus and translation occurs in the cytoplasm. [14]
While prokaryotes are able to undergo both cellular processes simultaneously, the spatial separation that is provided by the nuclear membrane prevents this coupling in eukaryotes. Eukaryotic elongation factor 2 (eEF2) is a regulateable GTP-dependent translocase that moves nascent polypeptide chains from the A-site to the P-site in the ribosome.
The mechanism of translation initiation differs in prokaryotes and eukaryotes. The 3' UTR is found immediately following the translation stop codon . The 3' UTR plays a critical role in translation termination as well as post-transcriptional modification .