- Precursor mRNA
Precursor mRNA (pre-mRNA), also termed heterogeneous nuclear RNA (hnRNA), is an immature single strand of messenger ribonucleic acid (
mRNA). pre-mRNA is synthesized from a DNAtemplate in the cell nucleusby transcription.
Once pre-mRNA has been completely processed, it is termed "mature
messenger RNA", "mature mRNA", or simply "mRNA".
Eukaryotic pre-mRNA exists only briefly before it is fully processed into mRNA. pre-mRNAs include two different types of segments,
exons and introns. Exons are segments that are retained in the final mRNA, while introns are removed in a process called splicing, which is performed by the spliceosome(except for self-splicing introns).
Additional processing steps attach modifications to the 5' and 3' ends of the pre-mRNA. These include a
5' capof 7-methylguanosine and a poly-A tail.
When a pre-mRNA strand has been properly processed to an mRNA sequence, it is exported out of the nucleus and eventually translated into a protein – a process accomplished in conjunction with
* [http://www.scienceden.com/mbiology/concepts/rna Scienceden.com RNA Article]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Precursor — Als Präkursor oder Prekursor (über engl. precursor aus lat. praecursor „Vorläufer“) bezeichnet man in der Chemie bei einer chemischen Synthese ein Molekül, das als Ausgangsprodukt (vgl. Edukt) betrachtet wird, aber auch durchaus selbst eine… … Deutsch Wikipedia
precursor RNA — any of the unprocessed RNA primary transcripts in the eukaryotic nucleus; see pre mRNA, pre rRNA, and pre tRNA … Medical dictionary
pre-mRNA — precursor messenger ribonucleic acid * * * pre messenger RNA any of the large RNA molecules constituting a primary transcript of a structural gene in eukaryotes, containing introns and exons and constituting the majority of the heterogeneous… … Medical dictionary
pre-mRNA — • precursor messenger ribonucleic acid … Dictionary of medical acronyms & abbreviations
let-7 microRNA precursor — Predicted secondary structure and sequence conservation of let 7 Identifiers Symbol let 7 Rfam … Wikipedia
mir-92 microRNA precursor family — Predicted secondary structure and sequence conservation of mir 92 Identifiers Symbol mir 92 Rfam … Wikipedia
mir-124 microRNA precursor family — Predicted secondary structure and sequence conservation of mir 124 Identifiers Symbol mir 124 Rfam … Wikipedia
mir-16 microRNA precursor family — mir 16 miR 16 microRNA secondary structure and sequence conservation. Identifiers Symbol mir 16 Rfam … Wikipedia
mir-17 microRNA precursor family — Predicted secondary structure and sequence conservation of mir 17 Identifiers Symbol mir 17 Rfam … Wikipedia
mir-24 microRNA precursor family — Predicted secondary structure and sequence conservation of mir 24 Identifiers Symbol mir 24 Rfam … Wikipedia