In molecular biology, the 5.8S ribosomal RNA (5.8S rRNA) is a

non-coding RNA A non-coding RNA (ncRNA) is a functional RNA molecule that is not Translation (genetics), translated into a protein. The DNA sequence from which a functional non-coding RNA is transcribed is often called an RNA gene. Abundant and functionally imp ...

component of the large subunit of the

eukaryotic The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

ribosome Ribosomes () are molecular machine, macromolecular machines, found within all cell (biology), cells, that perform Translation (biology), biological protein synthesis (messenger RNA translation). Ribosomes link amino acids together in the order s ...

and so plays an important role in

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 ...

. It is transcribed by

RNA polymerase I RNA polymerase 1 (also known as Pol I) is, in higher eukaryotes, the polymerase that only transcribes ribosomal RNA (but not 5S rRNA, which is synthesized by RNA polymerase III), a type of RNA that accounts for over 50% of the total RNA synthesiz ...

as part of the 45S precursor that also contains 18S and

28S rRNA 28S ribosomal RNA is the structural ribosomal RNA (rRNA) for the large subunit (LSU) of eukaryotic cytoplasmic ribosomes, and thus one of the basic components of all eukaryotic cells. It has a size of 25S in plants and 28S in mammals, hence th ...

. Its function is thought to be in ribosome translocation. It is also known to form

covalent A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs. The stable balance of attractive and repulsive forces between atom ...

linkage to the

p53 p53, also known as tumor protein p53, cellular tumor antigen p53 (UniProt name), or transformation-related protein 53 (TRP53) is a regulatory transcription factor protein that is often mutated in human cancers. The p53 proteins (originally thou ...

tumour suppressor protein. 5.8S rRNA can be used as a reference gene for

miRNA Micro ribonucleic acid (microRNA, miRNA, μRNA) are small, single-stranded, non-coding RNA molecules containing 21–23 nucleotides. Found in plants, animals, and even some viruses, miRNAs are involved in RNA silencing and post-transcri ...

detection. The 5.8S ribosomal RNA is used to better understand other rRNA processes and pathways in the cell. The 5.8S rRNA is homologous to the 5' end of non-eukaryotic

LSU rRNA Large subunit ribosomal ribonucleic acid (LSU rRNA) is the largest of the two major RNA components of the ribosome Ribosomes () are molecular machine, macromolecular machines, found within all cell (biology), cells, that perform Translation (b ...

. In eukaryotes, the insertion of ITS2 breaks LSU rRNA into 5.8S and 28S rRNAs. Some

flies Flies are insects of the Order (biology), order Diptera, the name being derived from the Ancient Greek, Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwin ...

have their 5.8 rRNA further split into two pieces.

Structure

L567.5 rRNA structure is approximately 150

nucleotides Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both o ...

in size and it consists of plenty of folded strands, some of which are presumed to be single stranded. This ribosomal RNA, along with the 28S and 5S rRNA as well as 46

ribosomal proteins A ribosomal protein (r-protein or rProtein) is any of the proteins that, in conjunction with rRNA, make up the ribosomal subunits involved in the cellular process of translation. ''E. coli'', other bacteria and Archaea have a 30S small subunit an ...

, forms the ribosomal large subunit (LSU). The 5.8S rRNA is initially transcribed along with the 18S and 28S rRNA in the 45S preribosomal RNA, along with the ITS 1 and ITS 2 (

Internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. ...

) and a 5’ and 3’ ETS (

External transcribed spacer External transcribed spacer (ETS) refers to a piece of non-functional RNA, closely related to the internal transcribed spacer, which is situated outside structural ribosomal RNAs (rRNA) on a common precursor transcript. ETS sequences characterist ...

). The 5.8S rRNA is located between the two ITS regions, with ITS1 separating it from the 18S rRNA in the 5' direction, and ITS2 separating it from the 28S rRNA in the 3' direction. The ITS and ETS are cleaved away during rRNA maturation. This is accomplished through a continuous cleavage pathway performed by both

endonuclease In molecular biology, endonucleases are enzymes that cleave the phosphodiester bond within a polynucleotide chain (namely DNA or RNA). Some, such as deoxyribonuclease I, cut DNA relatively nonspecifically (with regard to sequence), while man ...

and

exonuclease Exonucleases are enzymes that work by cleaving nucleotides one at a time from the end (exo) of a polynucleotide chain. A hydrolyzing reaction that breaks phosphodiester bonds at either the 3′ or the 5′ end occurs. Its close relative is th ...

enzymes, cutting the spacers at specific locations.

References

External links

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Arabidopsis 5.8S rRNA sequence

Rice 5.8S rRNA sequence
Ribosomal RNA {{molecular-cell-biology-stub