Biochem Accessory Folding

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  1. What does PDI stand for?
    Protein disulfide isomerase
  2. Where is PDI found?
    Eukaryotic ER
  3. What does PDI do?
    Catalyzes disuflide bond breaking and reformation, until a stable structure is reached
  4. What form must PDI be in to function?
    Its oxidized form
  5. What are the four key residues in the active PDI domains?
  6. What is the purpose of the second Cys?
    To detach a peptide bound Cys and allow reformation
  7. What is the fold adopted by PDI's domains?
    A thioredoxin fold
  8. How many domains does PDI have, what are their names?
    • Four,
    • - Alpha + Alpha'
    • - Beta + Beta'
  9. What does PPI stand for?
    Peptidyl prolyl cis-trans isomerase
  10. What are the five Molecular Chaperones?
    • 1. Heat Shock Protein 70
    • 2. Trigger Factor
    • 3. Chaperonin
    • 4. Heat Shock Protein 90
    • 5. Nucleoplasmins
  11. What are chaperonins?
    • Large multisubunit cagelike assemblies
    • - ATPases, GROEL/ES (Group i), CCT/TriC (Group ii)
  12. What are the four domains of GroEL?
    Apical, Intermediate and Equatorial
  13. What is the size and structure of GroEL?
    14 Identical Subunits, 60 kDa each
  14. What is the size and structure of GroES?
    Seven Identical Subunits, 10 kDa each
  15. Where is GroEL/ES found?
  16. Which domain is responsible for ATP hydrolysis?
  17. How big is GroEL's central cavity? What separates the two subunits?
    • 45 Angstroms
    • The N and C termini
  18. What changes occur with GroES binding?
    • - Large concerted movements
    • - Cavity volume doubles with widening and elongation
    • - ATPase activation
  19. What to the Apical helices initially bind to in GroEL?
    The unfolded protein
  20. What causes the apical helices to detatch from their initial companions in GroEL?
    GroES binding
  21. Why is stealing of the apical helices important for GroELES?
    Deprives substrate protein of binding sites, allow folding
  22. Generally, how many ATP bind to GroEL? When do they bind?
    Seven, before GroES association
  23. When does the misfolded protein bind to GroEL?
    After ATP binding
  24. What triggers ATP association?
    ATP hydrolysis on the trans ring (ADP present)
  25. When does bound ADP dissociate?
    With GroES binding to the trans ring
  26. What triggers ATP hydrolysis?
    No specific trigger, occurs after GroES binding, and ADP release
  27. How long does ATP hydrolysis take?
    Around 10s
  28. What triggers GroES release?
    Hydrolysis of ATP weakens GroEL/ES association
  29. What are the two models for Protein folding?
    • Anifsen Cage
    • Iterative Anealing
  30. Explain the Anifsen Cage model
    • - GroEL/ES provides the perfect microenvironment
    • - Small volume of cage means less room for error
    • - Hydrophillic walls prevent burying of hydrophobes
  31. Explain the Iterative Annealing Method
    • - ATP unfolded and refolded by stretching apical domain (helices)
    • - Stretching and subsquent release removes protein from local minima
  32. What are Eukaryote GroEL/ES-like proteins?
    Group II chaperonins
  33. What are some characteristics of Group II chaperonins?
    • - Eukaryotes
    • - Two rings, 8-9 subunits
    • - ATPase
    • - No lid (like GroEL/ES)
    •    - Lid formed from helical extensions
Card Set:
Biochem Accessory Folding
2014-12-15 02:51:07

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