Precursor mRNA
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It has been suggested that this article or section be merged into Messenger RNA. (Discuss) |
Precursor mRNA, more correctly termed heterogeneous nuclear RNA (hnRNA), is an immature single strand of messenger ribonucleic acid (mRNA). HnRNA is synthesized from a DNA template in the cell nucleus by a process called transcription.
Once hnRNA has been completely processed, it is termed "mature messenger RNA", "mature mRNA", or simply "mRNA".
Processing
Eukaryotic hnRNA exists only briefly before it is fully processed into mRNA. HnRNAs 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.
Additional processing steps attach modifications to the 5' and 3' ends of the hnRNA. These include a 5' cap of 7-methylguanosine and a poly-A tail.
When an hnRNA strand has been properly processed, becoming an mRNA sequence, it is exported out of the nucleus and eventually translated into a protein... a process accomplished in conjunction with ribosomes.
External links
Post-transcriptional modification |
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| Transcription - 5' cap - RNA splicing (Precursor mRNA, Intron/Exon, snRNP, Spliceosome, Alternative splicing) - Polyadenylation |
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Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
