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50S, roughly equivalent to the 60S ribosomal subunit in eukaryotic cells, is the larger subunit of the 70S ribosome of prokaryotes. The 50S subunit is primarily composed of proteins but also contains single-stranded RNA known as ribosomal RNA (rRNA). rRNA forms secondary and tertiary structures to maintain the structure and carry out the catalytic functions of the ribosome.
Archaeal ribosomes share the same general dimensions of bacteria ones, being a 70S ribosome made up from a 50S large subunit, a 30S small subunit, and containing three rRNA chains. However, on the sequence level, they are much closer to eukaryotic ones than to bacterial ones.
This ribosomal protein is a component of the 50S subunit. The protein binds 5S rRNA to form a stable complex. In turn 5S rRNA binds specifically to three proteins, L25, L18 and L5, forming a separate domain of the bacterial ribosome. [1] Protein L25 of E. coli is not essential for survival of the cells. [2] [3]
The ribosome of E. coli has about 22 proteins in the small subunit (labelled S1 to S22) and 33 proteins in the large subunit (somewhat counter-intuitively called L1 to L36). All of them are different with three exceptions: one protein is found in both subunits (S20 and L26), [ dubious – discuss ] L7 and L12 are acetylated and methylated forms ...
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]
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]
The 40S subunit contains a 18S ribosomal RNA (abbreviated 18S rRNA), which is homologous to the prokaryotic 16S rRNA. The 60S subunit contains a 28S rRNA that is homologous to the prokaryotic 23S ribosomal RNA. In addition, it contains a 5.8S rRNA that corresponds to the 5' end of the 23S rRNA, and a short 5S rRNA.
The ribosomal DNA includes all genes coding for the non-coding structural ribosomal RNA molecules. Across all domains of life, these are the structural sequences of the small subunit (16S or 18S rRNA) and the large subunit (23S or 28S rRNA). The assembly of the latter also include the 5S rRNA as well as the additional 5.8S rRNA in eukaryotes.