Eukaryotic+mRNA+Capping+Poly-A+tails



Eukaryotic mRNA Capping Poly-A tails occur when RNA is created, then mRNA copies one strand, the ends are modified with 5’ and 3’ ends, and then a poly adenylation occurs adding a strand of A nucleotides to the end. This is important to cellular physiology because it helps the cell to determine whether or not the mRNA is ready to be exported and translated into a protein. The ends also help to determine the type of protein that it will be translated into (Alberts, 2008). The history of this topic’s research is that polyadenylation was first discovered in 1960s as an enzymatic activity that could polymerase ATP (Edmonds, 1960). The actual known function of this wasn’t known until 1971, when Polyadenylated tail sequences were discovered in RNA. At first it was only thought to cap on the 3’ end of mRNA but then later found that it is also important in export and translation (Edmonds, M., 2002). Different research articles have used this technique of mRNA capping and poly-A tails to identify or create different outcomes for their mRNA sequence.

1. The Importance of polyadenylation in this paper is that by adding yPAP to the cleavage system of mRNA, they were able to achieve a specific poly-a tail addition. They discovered that at least some of the yeast polyadenylation-related proteins work in the plant system (Zhao, 2011). This could potentially become useful in crossing bacterial and plant genes for a future study.

2. The mRna capping technique is important in this paper because it forms a covalent complex with RNA viruses at the 5’ phosphorylated viral mRNA start sequence and the mRNA is capping is catalyzed by the RNA. The structural identification of mRNA is the 5’ terminal cap structure. This is what distinguishes mRNA from other types of RNA and makes it recognizable for export and translation (Ogino, 2011).

3. The importance of this technique in this paper is that the cap and the poly-a tail are mutually dependent as regulators of successful translation. They wanted to determine whether there was a functional relationship between the 5’ end of mRNA and the poly- a tail. They found that interdependence exists between the 5’ end and the poly-a tail in order to achieve an efficient function for translation. Although, they found that by adding either or there was an increased efficiency, but it was optimal with both. I learned that there is a mutual dependence for the poly-a tail and the 5’ end in order to carry out successful translation (Gallie, 1991).

__References:__


 * Alberts, B. (2008). //Molecular biology of the cell // (5th ed.). New York: Garland Science.
 * Edmonds, Mary; Abrams, Richard (1960). [|"Polynucleotide Biosynthesis: Formation of a Sequence of Adenylate Units from Adenosine Triphosphate by an Enzyme from Thymus Nuclei"] . //The Journal of Biological Chemistry// 235 (4): 1142–9. [|PMID] [|13819354].
 * Edmonds, M (2002). "A history of poly A sequences: from formation to factors to function". //Progress in Nucleic Acid Research and Molecular Biology Volume 71//. Progress in Nucleic Acid Research and Molecular Biology 71. pp. 285–389. [|doi] : [|10.1016/S0079-6603(02)71046-5] . [|ISBN] [|978-0-12-540071-8].
 * Gallie, D. R., 1991. The cap and poly(A) tail function synergistically to regulate mRNA translational efficiency. //Genes & Development// 5: 2108-2116. Doi: 10.1101/gad.5.11.2108
 * Zhao, H., Zheng, J., and Li, Q. Q., 2011. A Novel Plant in Vitro Assay System for Pre-mRNA Cleavage during 3’ – End Formation. //Plant Physiology// 157: 1546-1554. Doi: 0.1104/pp.111.179465