Bio 3000 - RNA Editing

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Bio 3000 - RNA Editing
2013-04-22 13:57:02

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  1. What is RNA editing?
    The changing of an RNA sequence from it's transcribed sequence to something else.
  2. What Organelle RNAs demonstrate editing?
    • Nuclear RNAs
    • Mitochondrial RNAs
    • Chloroplast RNAs
    • Viral RNA
  3. What Nuclear RNAs are editing?
    • rRNA
    • mRNA
    • tRNA
  4. What Mitochondrial RNAs are edited?
    • tRNAs
    • mRNAs
    • rRNAs
  5. What Chloroplast RNAs are edited?
  6. What specific Virus demonstrates RNA editing?
    Hepatitis Delta Virus.
  7. What are some examples of RNA editing?
    • A-to-I Conversion.
    • C-to-U Conversion.
    • U Instertion/Deletion
    • Insertion of C Residues.
  8. What is another name for C-to-U conversion?
  9. What does Deamination refer to?
    C-to-U conversion.
  10. In conversion of A-to-I, what is the I read as?
    Guanine (G).
  11. Does RNA editing occur in Prokaryotes?
    No, none has been observed.
  12. If a given amino acid sequence is,


    Is it always possible to determine the initial DNA sequence?
    No, because RNA editing sometimes changes the transcript.
  13. Eubacteria and Archaea are examples of?
  14. Where does insetion of U residues occur? (What organelle).
    In the Mitochondria of Trypanosomes.
  15. What is a Trypanosome?
    A single celled Parasitic Protozoan.
  16. Where does insertion of C Residues occur? (What Organelle)
    Slime Mold Mitochondria.
  17. What RNAs tend to be affected by C Insertion?
    rRNA, tRNA and mRNA
  18. In Mammals, where does C-to-U converstion occur?
    In the intestine (Affects Apoprotein B mRNA).
  19. In Plants where does C-to-U conversion occur?
    In Mitochondria and Chloroplasts.
  20. Where does A-to-I editing tend to occur in mammals?
    • In the nucleus.
    •   Affects Glutamate and Serotonin 2c Receptors.
  21. What specific edit does Hepatitis Delta Virus demonstrate?
    A-to-I conversion.
  22. How was U-Insertion first discovered?
    Researcher noticed an mRNA product did not match it's "parent" DNA.
  23. What was the observation in Trypanosome RNA that lead to U-Insertion discovery?
    A -1 Frameshift at the C-Terminus, Caused by addition of four U's.
  24. What protein was used to first identify U-Insertion?
    Trypanosome Cox2p.
  25. How is it determined where U insertion/Deletion should occur?
    • Guide RNAs will base pair to the site.
    • Often, editing creates sites for further modification.
  26. How is the exact site of U insertion/deletion  defined?
    Bulges at the site (Not all Base Pairings are canonical).
  27. What is the role of anchor sequences in RNA editing?
    Sites of binding for the guide RNA. They do not take part in the actual editing but serve help complimentarity.
  28. One U is always modified for each editing event. True or False?
    False. Multiple U's can be edited in each event.
  29. What enzyme is responsible for A-to-I editing?
    Adenosine Deaminase acting on RNA (ADAR).
  30. What are the ADARs found in humans?
    ADAR 1, ADAR 2 and ADAR 3.
  31. Which human ADAR is found in the brain?
    ADAR 3
  32. What type of molecules does Adenosine Deaminase acting on RNA target?
    Double Stranded RNA.
  33. What are two key roles of ADARs?
    • Defense (Interfering with foreign RNA).
    • Control of splicing.
  34. How does and ADAR act as a defense system?
    Through non-specific editing.
  35. How does an ADAR act to control splicing?
    Through Specific Editing.
  36. What are some examples of ADARs that undergo Deamination?
    • Glutamate Subunit Receptor B.
    • Serotonin Receptor 5-HT2c.
  37. How does A-to-I editing affect the Glutamate receptor?
    Changes the Glutamine (CAG) to an Argenine (CIG "CGG").
  38. How does A-to-I editing affect the Serotonin Recpetor 5-HT2c?
    • It can change 3 amines in the GCPR's cytoplasmic loop.
    •  Lle (AUA) -> Met (AUI) -> Val (IUA/IUI)
    •  Asn (AAU) ->Asp (IAU)/Ser (AIU) -> Gly (IIU)
    •  Lle (AUU) -> Val (IUU)
  39. Where is Apo-B found?
    In the Liver.
  40. How is the Apo-B48 protein produced from Apo-B mRNA?
    • The CAA undergoes C-to-U editing becoming UAA (A transaltional STOP codon).
    • The resulting protein is the stunted N-Terminus.
  41. HOw is the Apo-B100 protein formed?
    • The mRNA is transcribed without any unique editing.
    • The protein has two domains (N and C Termini).
  42. What are the two domains in the Apo-B100 protein?
    • The N-Terminus (Lipid Association)
    • The C-Terminus (Binds to Membrane LDL receptors).