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Precursor mRNA

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noun, plural: precursor mRNAs

An immature or incompletely processed mRNA molecule in eukaryotes that needs to be processed before it becomes a fully functional mature mRNA for transport into the cytoplasm


The mRNA is a type of RNA involved in protein synthesis. It is synthesized based on DNA template on the nucleus. In eukaryotes, it needs to be processed before it can be fully functional, conveying the genetic code to the ribosomes (site of protein synthesis in the cytoplasm).

The pre-mRNA is the initial form of mRNA in eukaryotes. It is formed by transcribing the genetic information from DNA molecule. Before it is moved into the cytoplasm for translation at the ribosomal site, the pre-mRNA undergoes extensive processing within the nucleus.

The pre-mRNA is the first form of RNA created through transcription in protein synthesis. The pre-mRNA lacks structures that a mature messenger RNA requires. First, all introns have to be removed from the transcribed RNA through a process known as splicing. Before the RNA is ready for export, a Poly(A)tail is added to the 3' end of the RNA and a 5' cap is added to the 5' end.


  • pre-mRNA

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