Polyadenylation, mRNA processing

Polyadenylation This process is the addition of many AMP molecules to the 3 end of the RNA molecule. Once bound it is known as a poly A tail, since it is comprised of 100 or more such adenylate (AMP) residues. The tail is thought to stabilise the mRNA molecule in the cytosol, probably by preventing hydrolysis by an RNAase. 

RADPRE A Computational Program for Identification of Differential mRNA Processing Including Alternative Polyadenylation... 

Zheng J, Xing D, Wu X, Shen Y, Kroll DM, Ji G, Li QQ (2011) Ratio-based analysis of differential mRNA processing and expression of a polyadenylation factor mutant pcfs4 using arabidopsis... 

Figure 37-13. Mechanisms of alternative processing of mRNA precursors. This form of RNA processing involves the selective inclusion or exclusion of exons, the use of alternative 5 donor or 3 acceptor sites, and the use of different polyadenylation sites.

Figure 20.20 Summary of transcription, RNA processing and polypeptide synthesis. Polymerisation of the DNA template by RNA polymerase produces pre-mRNA (the primary transcript) this is transcription. The pre-mRNA is now processed, which involves capping, polyadenylation, editing and splicing (see text). The resultant mRNA transfers from the nucleus to the cytosol, where amino acids are polymerised to produce a polypeptide using the instructions present in the codons of the mRNA.

Splicing is just one of the fonr processes that can modify the mRNA molecnle prior to transfer into the cytosol. The other three are cap formation, polyadenylation and editing of RNA. These are colectively known as RNA processing... 

Fig. 1.46. Alternative polyadenylation in the expression of calcitonin genes of rat. The primary transcript of the calcitonin gene possesses two polyadenylation sites. One site is nsed in the processing of RNA in the thyroid, another site in the brain, and yet another in nerve tissne. The translation of the two mRNAs creates two pre-hormones, from which two different polypeptide hormones (calcitonin and the calcitonin-related peptide", or CGRP) are created via proteolysis.

Cai X, Hagedorn CH, Cullen BR. Human microRNAs are processed from capped, polyadenylated transcripts that can also function as mRNAs. RNA 2004 10 1957-1966. 

Skaar, D.A. Greenleaf, A.L. The RNA polymerase II CTD kinase CTDK-I affects pre-mRNA 3 -cleavage/polyadenylation through the processing component Ptilp. Mol. Cell., 10, 1429-1439 (2002)... 

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