Does poly A tail protect mRNA from degradation?
Introduction. The 5-methylguanosine cap and the poly(A) tail both contribute to protect eukaryotic mRNAs against degradation. Deadenylation is the initial and rate-limiting step of the general mRNA decay pathway [1].
Does the poly A tail increase mRNA stability?
Polyadenylate-binding proteins (PABPs) bind poly(A) tails and can increase or reduce mRNA stability and translation.
Does poly A tail affect translation?
The poly(A) tail can also stimulate translation and cooperates with the cap structure in a synergistic fashion. The eukaryotic initiation factor eIF4G plays a central part as a multifunctional adapter, which brings together various components of the translation apparatus.
What happens in mRNA degradation?
Most mRNAs are degraded by a deadenylation-dependent pathway in which the poly(A) tail is degraded by the CCR4-NOT or PARN. Subsequently, the 5′ cap of the mRNA is removed by the DCP1-DCP2 decapping complex. Following cap removal, the mRNA is degraded by the XRN1 exoribonuclease in a 5′ to 3′ direction.
How does poly-A tail prevent degradation?
Then an enzyme called poly-A polymerase adds a chain of adenine nucleotides to the RNA. This process, called polyadenylation, adds a poly-A tail that is between 100 and 250 residues long. The poly-A tail makes the RNA molecule more stable and prevents its degradation.
What happens if poly-A polymerase is inactivated?
If poly-A polymerase were inactivated what would happen? mRNA transcript would be broken down. If tRNA were to stop working what would happen? Translation would stop, proteins would not be delivered to ribosomes.
Why are some poly A tails longer?
At the end of each mRNA molecule is a poly(A) tail comprised of tens to hundreds of nucleotides called adenosines. The length of these tails can vary greatly between different mRNAs, and longer poly(A) tails are thought to improve translation and increase mRNA stability (Sachs, 1990).
Why are some poly A tails longer than others?
How does poly A tail prevent degradation?
How is mRNA targeted degradation?
Most mRNA degradation occurs using the CCR4/Not complex, targeted to the 3′UTR of the mRNA and directed by elements and proteins binding to this part of the mRNA.
What prevents mRNA degradation?
After export to the cytoplasm, mRNA is protected from degradation by a 5′ cap structure and a 3′ poly adenine tail. In the deadenylation dependent mRNA decay pathway, the polyA tail is gradually shortened by exonucleases.
How does the poly-A tail stabilize mRNA?
At the other end of the mRNA, the poly(A) tail is bound by poly(A) binding proteins (PABPs), which facilitate mRNA export from the nucleus and enhance protein synthesis through interactions with translation initiation factors [17]. Poly(A) also stabilizes mRNA molecules by preventing exoribonucleolytic decay.