Messenger RNA 5 -capping

Shuman S. What messenger RNA capping tells us about eukaryotic evolution. Nat. Rev. Mol. Cell. Biol. 2002 3 619-625. 

Inducible operons 1642 4. Messenger RNA, Caps, and Polyadenylate Tails... 

Poxyvirus DNA-Dependant RNA polymerase Messenger-RNA capping enzyme Poly(A) polymerase Nucleasess DNA-Dependant nucleotide phosphohydrolase Topoisomerase Protein kinase... 

Reovirus RNA-Dependant RNA polymerase Nucleotide phosphohydrolase Messenger-RNA capping enzyme... 

Preiss, T. and M.W. Hentze, Dual function of the messenger RNA cap structure in poly(A)-tail- promoted translation in yeast. Nature, 1998. 392(6675) p. 516-20. 

Figure 35-10. The cap structure attached to the 5 terminal of most eukaryotic messenger RNA molecules. A 7-methylguanosine triphosphate (black) is attached at the 5 terminal of the mRNA (shown in blue), which usually contains a 2 -0-methylpurine nucleotide.

The answer is e. (Katzung, p 842.) Ribavirin most likely interferes with guanosine triphosphate synthesis, resulting in inhibition of capping of viral messenger RNA and viral RN A-dependent RNA polymerase. It is effective in moderating infections with respiratory syncytial virus. 

Although its mechanism of action has not been fully elucidated, it appears to interfere with the synthesis of guanosine triphosphate, to inhibit capping of viral messenger RNA, and to inhibit the viral RNA-dependent RNA polymerase of certain viruses. Ribavirin triphosphate inhibits the... 

Figure 5.29. Modification of mRNA. Messenger RNA in eukaryotes is modified after transcription. A nucleotide "cap" structure is added to the 5 end, and a poly(A) tail is added at the 3 end.

The messenger RNA is also given a cap and a polyadenine tail before being sent to the cytosol. (Fig 12.4)... 

Messenger RNA (mRNA) contains a cap structure and a poly(A) tail. 

Messenger RNA, produced by RNA polymerase II, is capped at the 5 end and has a poly(A) tail added at the 3 end. Introns (segments that do not code for protein) are removed, and exons (segments that code for protein) are spliced together. 

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