What is alternative polyadenylation?
Alternative polyadenylation (APA) is a widespread mechanism of gene regulation that generates distinct 3′ ends in transcripts made by RNA polymerase II. APA is tissue specific and globally regulated in various conditions, such as cell proliferation and differentiation, and in response to extracellular cues.
What is the significance of alternative polyadenylation of mRNA transcript?
Alternative polyadenylation (APA) is emerging as a widespread mechanism used to control gene expression. Like alternative splicing, usage of alternative poly(A) sites allows a single gene to encode multiple mRNA transcripts.
Are all mammalian mRNAs spliced and polyadenylated?
On mRNAs, the poly(A) tail protects the mRNA molecule from enzymatic degradation in the cytoplasm and aids in transcription termination, export of the mRNA from the nucleus, and translation. Almost all eukaryotic mRNAs are polyadenylated, with the exception of animal replication-dependent histone mRNAs.
How is polyadenylation regulated?
The majority of examples of polyadenylation regulated by auxiliary signals have been detected in the genomes of viruses and are commonly associated with switches in the viral life cycle. Examples of viral auxiliary elements are found in the SV40, adenovirus, hepatitis B, and several retroviral pre-mRNAs.
What is the polyadenylation signal?
Polyadenylation (or Poly(A)) signal, site and tail The polyadenylation or Poly(A) is the process required for the synthesis of messenger RNA (mRNA) in which an endonucleolityc RNA cleavage is coupled with synthesis of polyadenosine monophosphate (adenine base) on the newly formed 3′ end.
What is mRNA editing or splicing?
Abstract. In eukaryotes, nascent RNA transcripts undergo an intricate series of RNA processing steps to achieve mRNA maturation. RNA editing and alternative splicing are two major RNA processing steps that can introduce significant modifications to the final gene products.
Is polyadenylation a post transcriptional modification?
Alternative polyadenylation (APA) is an important post-transcriptional regulatory mechanism that processes RNA products depending on its 3′-untranslated region (3′-UTR) specific sequence signal.
Does bacterial mRNA have a 5 cap?
In eukaryotes, the 5′ end of the mRNA is protected from 5′ to 3′ exonucleolytic activity by the presence of the 5′ cap structure. In prokaryotes, the 5′ end of the newly transcribed mRNA is not further modified and retains the 5′ triphosphate.
What happens if there is a mutation in the 5 UTR?
5′ Untranslated regions (UTRs) are noncoding regions of messenger RNAs (mRNAs). Mutations that disrupt the functional elements of the 5′-UTR are often associated with diseases. Single nucleotide polymorphisms (SNPs) in the 5′-UTR are associated with individual’s drug response and disease risk.