Ribosomal particles are denoted according to their
sedimentation coefficient
In chemistry, the sedimentation coefficient () of a particle characterizes its sedimentation (tendency to settle out of suspension) during centrifugation. It is defined as the ratio of a particle's sedimentation velocity to the applied accelera ...
s in
Svedberg units. The 60S subunit is the large subunit of
eukaryotic 80S ribosomes, with the other major component being the
eukaryotic small ribosomal subunit (40S)
The eukaryotic small ribosomal subunit (40S) is the smaller subunit of the 80S, eukaryotic 80S ribosomes, with the other major component being the eukaryotic large ribosomal subunit (60S), large ribosomal subunit (60S). The "40S" and "60S" names o ...
. It is structurally and functionally related to the
50S subunit of
70S prokaryotic ribosomes.
However, the 60S subunit is much larger than the prokaryotic 50S subunit and contains many additional protein segments, as well as
ribosomal RNA
Ribosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal ...
expansion segments.
Overall structure
Characteristic features of the large subunit, shown below in the "Crown View", include the central protuberance (CP) and the two stalks, which are named according to their bacterial protein components (L1 stalk on the left as seen from the subunit interface and L7/L12 on the right). There are three binding sites for
tRNA
Transfer ribonucleic acid (tRNA), formerly referred to as soluble ribonucleic acid (sRNA), is an adaptor molecule composed of RNA, typically 76 to 90 nucleotides in length (in eukaryotes). In a cell, it provides the physical link between the gene ...
, the A-site, P-site and E-site (see article on
protein translation
In biology, translation is the process in living cells in which proteins are produced using RNA molecules as templates. The generated protein is a sequence of amino acids. This sequence is determined by the sequence of nucleotides in the RNA. T ...
for details).
The core of the 60S subunit is formed by the
28S ribosomal RNA (abbreviated 28S rRNA), which is homologous to the prokaryotic
23S rRNA, which also contributes the active site (
peptidyl transferase
The peptidyl transferase center (, PTC) is an Aminoacyltransferases, aminoacyltransferase ribozyme (RNA enzyme) located in the large subunit of the ribosome. It forms peptide bonds between adjacent amino acids during the Translation (genetics), ...
center, PTC) of the ribosome.
The rRNA core is decorated with dozens of proteins. In the figure "Crystal Structure of the Eukaryotic 60S Ribosomal Subunit from ''T. thermophila''", the ribosomal RNA core is represented as a grey tube and expansion segments are shown in red. Proteins which have homologs in eukaryotes, archaea and bacteria are shown as blue ribbons. Proteins shared only between eukaryotes and archaea are shown as orange ribbons and proteins specific to eukaryotes are shown as red ribbons.
60S ribosomal proteins
The table "60S ribosomal proteins" shows the individual protein folds of the 60S subunit colored by conservation as above. The eukaryote-specific extensions, ranging from a few residues or loops to very long alpha helices and additional domains, are highlighted in red.
Historically, different nomenclatures have been used for ribosomal proteins. For instance, proteins have been numbered according to their migration properties in
gel electrophoresis
Gel electrophoresis is an electrophoresis method for separation and analysis of biomacromolecules (DNA, RNA, proteins, etc.) and their fragments, based on their size and charge through a gel. It is used in clinical chemistry to separate ...
experiments. Therefore, different names may refer to homologous proteins from different organisms, while identical names do not necessarily denote homologous proteins. The table "60S ribosomal proteins" cross-references the human ribosomal protein names with yeast, bacterial, and archaeal homologs.
Further information can be found in the
ribosomal protein gene database (RPG).
See also
*
Eukaryotic small ribosomal subunit (40S)
The eukaryotic small ribosomal subunit (40S) is the smaller subunit of the 80S, eukaryotic 80S ribosomes, with the other major component being the eukaryotic large ribosomal subunit (60S), large ribosomal subunit (60S). The "40S" and "60S" names o ...
References
External links
Ribosomal Protein Gene Database (RPG)
{{Ribosome subunits
Ribosomal RNA