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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.
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.
Electron micrographs of stained cell-free protein synthesis reactions revealed branched assemblies in which strings of ribosomes are linked to a central DNA fibre. [27] DNA isolated from bacterial cells co-sediment with ribosomes, further supporting the conclusion that transcription and translation occur together. [26]
Initiation of translation in bacteria involves the assembly of the components of the translation system, which are: the two ribosomal subunits (50S and 30S subunits); the mature mRNA to be translated; the tRNA charged with N-formylmethionine (the first amino acid in the nascent peptide); guanosine triphosphate (GTP) as a source of energy, and the three prokaryotic initiation factors IF1, IF2 ...
Inside eukaryotic cells, there is a balance between the processes of translation and mRNA decay. Messages that are being actively translated are bound by ribosomes , the eukaryotic initiation factors eIF-4E and eIF-4G , and poly(A)-binding protein . eIF-4E and eIF-4G block the decapping enzyme ( DCP2 ), and poly(A)-binding protein blocks the ...
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] In bacteria, it proceeds at a rate of 15 to 20 amino acids added per second (about 45-60 nucleotides per second).
During translation, ribosomes synthesize polypeptide chains from mRNA template molecules. In eukaryotes, translation occurs in the cytoplasm of the cell, where the ribosomes are located either free floating or attached to the endoplasmic reticulum. In prokaryotes, which lack a nucleus, the processes of both transcription and translation occur ...