Mature mRNA

mRNA precursors are synthesized during transcription as a complementary strand to the template strand of DNA. Afterwards the introns are spliced out of the precursor mRNA, a 5’ cap is added, the 3’ end is polyadenylated, and the mature mRNA is transported out of the nucleus. In the cytoplasm, the mRNA molecule recruits ribosomes and translation is initiated.

The structure of a mature mRNA molecule can be seen in the next image:

As it can be seen in the image above all mRNAs have a polyA tail attached in the 3' end. This can be advantageously used as the binding region for the oligo(dT) primers in the process of cDNA synthesis.