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Mechanism of messenger RNA (mRNA) degradation. The degradation of mRNA begins on the newly cytoplasmic mRNA. The decay process is regulated by elements on each end of the mRNA. The mRNA has a 7-methyl-guanosine cap at the 5′ end and a poly(A) tail at the 3′ end. The poly(A) length is approximately 60 nucleotides upon export. In the cytoplasm, the mRNA is initially deadenylated by Pan2/3 and then primarily by the Ccr4/Pop2/Not deadenylase complex, resulting in a median poly(A) length of approximately 30 nucleotides. Once the poly(A) tail is shortened to a length that is no longer able to bind Pab1p, the mRNA can be degraded from the 3′5′ direction by the exosome. The 5′3′ degradation pathway requires the mRNA to be first decapped by the decapping complex Dcp1/2 and then degraded by the Xrn1p exonuclease enzyme.

Mechanism of messenger RNA (mRNA) degradation. The degradation of mRNA begins on the newly cytoplasmic mRNA. The decay process is regulated by elements on each end of the mRNA. The mRNA has a 7-methyl-guanosine cap at the 5′ end and a poly(A) tail at the 3′ end. The poly(A) length is approximately 60 nucleotides upon export. In the cytoplasm, the mRNA is initially deadenylated by Pan2/3 and then primarily by the Ccr4/Pop2/Not deadenylase complex, resulting in a median poly(A) length of approximately 30 nucleotides. Once the poly(A) tail is shortened to a length that is no longer able to bind Pab1p, the mRNA can be degraded from the 3′5′ direction by the exosome. The 5′3′ degradation pathway requires the mRNA to be first decapped by the decapping complex Dcp1/2 and then degraded by the Xrn1p exonuclease enzyme.

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Messenger RNA (mRNA) degradation is an important element of gene expression that can be modulated by alterations in translation, such as reductions in initiation or elongation rates. Reducing translation initiation strongly affects mRNA degradation by driving mRNA toward the assembly of a decapping complex, leading to decapping. While mRNA stabilit...

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... the 3 ′ end of an mRNA is the poly-adenosine or poly(A) tail. Sim- ilarly, linked to the 5 ′ end is a methyl-7-guanosine cap ( Figure 1). Integrating these ends is the transla- tion initiation factor eIF4F, which is the cap-binding complex (see below). ...
Context 2
... the 5 ′ cap must be exposed; therefore suggesting that the translation initiation factors eIF4G and eIF4E must be released from the mRNA. 25 Finally, following the recruitment of the decapping complex, the phosphate bond that links the cap to the body of the mRNA is hydrolyzed, leaving a monophosphorylated 5 ′ end (Figure 1). 21,26 Removal of the mRNA cap allows 5 ′ →3 ′ degradation to proceed by the exonuclease Xrn1p. ...
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... Removal of the mRNA cap allows 5 ′ →3 ′ degradation to proceed by the exonuclease Xrn1p. 23 Alternatively, oligoadenylated mRNA can be degraded from the 3 ′ →5 ′ direction by the exosome (Figure 1). The core exosome complex consists of a ring of six RNase PH-like proteins and three smaller RNA-binding proteins, which are required for its for- mation and stabilization. ...

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... mRNA degradation can be triggered by various quality control mechanisms (e.g. nonsensemediated decay), but degradation is also thought to be cou-pled to the translation of the mRNA by ribosomes (3,4). Seminal work established the main degradation pathway in eukaryotes: mRNA is deadenylated by the Ccr4-Not complex, decapped by the Dcp1-Dcp2 complex, and degraded by the highly processive 5 -3 exoribonuclease Xrn1 (5)(6)(7)(8)(9)(10). ...
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