As DNA is transcribed into messenger RNA, it must take certain precautions in order for the messenger RNA to be transported safely out of the nucleus as well as initiating translation in proteins. One of these precautions is the addition of the poly(A) tail at the end of the messenger RNA. After the entire messenger RNA strand has been transcribed, poly(A) polymerase binds to the RNA by magnesium ions and uses ATP to add approximately 250 adenosine nucleotides to the end of the messenger RNA strand. Poly(A) binding proteins then attach to the poly(A) tail to guide it through the remainder of the translation process. Without the poly(A) tail the messenger RNA could potentially be cleaved at the wrong location or form the incorrect or mutated protein.
Megan Roadley
Goodsell, David. “Poly(A) Polymerase”. Protein Data Bank. October 2008. Accessed online 6 September 2009. http://www.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/pdb106_1.html.
