precursor messenger RNA
precursor messenger rna
An immature or incompletely processed mRNA molecule that needs to be processed before it becomes a fully functional mature mRNA. Pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription and lacks structures that the mRNA 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.