What is the 3'UTR site of mRNA?
It is an untranslated region of the mRNA.
DNA as well as RNA has a 3' (3 prime) and a 5' (5 prime) end. This has to do with the direction in which the sequence is read. The UTR stands for untranslated region .
Translation is the process of building a protein from the mRNA. As the name implies, the 3'UTR does not translate into a piece of the protein.
As you can see in the image below, there are several steps before you get to a mature mRNA. The mRNA contains not only the region that is finally translated into the protein (the exons), but also has an untranslated region at the 5'end and at the 3'end , also called the leader- and trailer sequence respectively.
The 3'UTR is the region immediately after the signal for the termination of the coding region (the stop codon).
The cap and the poly(A)tail mentioned in the image are added to the mRNA to prevent the mRNA from being degraded by enzymes in the cell.