Polyadenylation

Polyadenylation is the addition of a poly(A) tail to an RNA molecule. The poly(A) tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA (mRNA) for translation. It, therefore, forms part of the larger process of gene expression.

The process of polyadenylation begins as the transcription of a gene finishes, or terminates. The 3'-most segment of the newly-made RNA is first cleaved off by a set of proteins; these proteins then synthesize the poly(A) tail at the RNA's 3' end. In some genes, these proteins may add a poly(A) tail at any one of several possible sites. Therefore, polyadenylation can produce more than one transcript from a single gene (alternative polyadenylation), similar to alternative splicing.

The poly(A) tail is important for the nuclear export, translation, and stability of mRNA. The tail is shortened over time, and, when it is short enough, the mRNA is enzymatically degraded. However, in a few cell types, mRNAs with short poly(A) tails are stored for later activation by re-polyadenylation in the cytosol. In contrast, when polyadenylation occurs in bacteria, it promotes RNA degradation. This is also sometimes the case for eukaryotic non-coding RNAs.

Read more about Polyadenylation:  Background On RNA, Cytoplasmic Polyadenylation, Tagging For Degradation in Eukaryotes, In Prokaryotes and Organelles, Evolution, History

Other articles related to "polyadenylation":

Polyadenylation - History
... Polyadenylation was first identified in 1960 as an enzymatic activity in extracts made from cell nuclei that could polymerise ATP, but not ADP, into polyadenine ... first to be protection of the 3' end of the RNA from nucleases, but later the specific roles of polyadenylation in nuclear export and translation were ... The polymerases responsible for polyadenylation were first purified and characterized in the 1960s and 1970s, but the large number of accessory proteins that control this process ...
Messenger RNA - Synthesis, Processing, and Function - Eukaryotic Pre-mRNA Processing - Polyadenylation
... Polyadenylation is the covalent linkage of a polyadenylyl moiety to a messenger RNA molecule ... Polyadenylation is also important for transcription termination, export of the mRNA from the nucleus, and translation ... Polyadenylation occurs during and immediately after transcription of DNA into RNA ...
Simian Virus 40 Late Polyadenylation Signal (SVLPA)
... The simian virus 40 late polyadenylation signal (SVLPA) is an RNA element which promotes efficient polyadenylation ...
TTATT - In Prokaryotes and Organelles
... Successive rounds of polyadenylation and degradation of the 3' end by polynucleotide phosphorylase allows the degradosome to overcome these secondary structures ... Destabilising polyadenylation targets both mRNA and noncoding RNAs ... Plant mitochondria have only destabilising polyadenylation, and yeast mitochondria have no polyadenylation at all ...
SYMPK
... plasma membrane • tight junction Biological process • mRNA polyadenylation • cell adhesion • positive regulation of protein dephosphorylation Sources ... a nuclear protein that functions in the regulation of polyadenylation and promotes gene expression ... The protein forms a high-molecular weight complex with components of the polyadenylation machinery ...