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In molecular biology, the 5.8S ribosomal RNA (5.8S rRNA) is a non-coding RNA component of the large subunit of the eukaryotic ribosome and so plays an important role in protein translation. It is transcribed by RNA polymerase I as part of the 45S precursor that also contains 18S and 28S rRNA. Its function is thought to be in ribosome ...
Initial structures of eukaryotic ribosomes were determined by electron microscopy. First 3D structures were obtained at 30–40 Å resolution for yeast [5] and mammalian ribosomes. [6] [7] Higher resolution structures of the yeast ribosome by cryo-electron microscopy allowed the identification of protein and RNA structural elements. [8]
In addition, L31 is known to exist in two forms, the full length at 7.9 kilodaltons (kDa) and fragmented at 7.0 kDa. This is why the number of proteins in a ribosome is of 56. Except for S1 (with a molecular weight of 61.2 kDa), the other proteins range in weight between 4.4 and 29.7 kDa. [10]
Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and translate the latter into proteins. [1]
The first atomic structures of the ribosome complexed with tRNA and mRNA molecules were solved by using X-ray crystallography by two groups independently, at 2.8 Å [44] and at 3.7 Å. [45] These structures allow one to see the details of interactions of the Thermus thermophilus ribosome with mRNA and with tRNAs bound at classical ribosomal sites.
Ribosomes are the macromolecular machines that are responsible for mRNA translation into proteins. The eukaryotic ribosome, also called the 80S ribosome, is made up of two subunits – the large 60S subunit (which contains the 25S [in plants] or 28S [in mammals], 5.8S, and 5S rRNA and 46 ribosomal proteins) and a small 40S subunit (which contains the 18S rRNA and 33 ribosomal proteins). [6]
[8] After the new amino acid is added to the chain, and after the tRNA is released out of the ribosome and into the cytosol, the energy provided by the hydrolysis of a GTP bound to the translocase EF-G (in bacteria) and a/eEF-2 (in eukaryotes and archaea) moves the ribosome down one codon towards the 3' end. The energy required for translation ...
The polypeptides ribosomes produce go on to be cell structural proteins, enzymes, and many other things. [3] Ribosomes can also sometimes be associated with chloroplasts and mitochondria but these are not membrane bound. [3] The image shows a membrane-bound ribosome synthesizing a protein into the lumen of the endoplasmic reticulum.