Review Cards

Question 1

eEF1A:

Answer 1

• elongation factor that brings canonical tRNAs to the A-site of the ribosome during translation.
• if the unfolded protein fails to properly fold, eEF1A will initiate degradation of the unfolded chain.

Question 2

Bonds in Ub-pathway:

Answer 2

1. peptide (Ub-fusion protein)
   
   • cleaved by Ub-carboxy-terminal-hydrolase
2. thioester (mono-Ub and E1)
   
   • non-covalent E1-Ub adenylate
   • intramolecular rearrangement: Ub-G76 thioester linkage with E1-Cysteine
3. isopeptide (Ub and substrate)
   
   • Ub-G76 and substrate e-amino group lysine

Question 3

GroEL structure and function:

Answer 3

• multi-subunit; four rings
• large hydrophobic cavities both ends of cylinder bind misfolded proteins
• synchronous hydrolysis of 7 ATP causes twist of subunits, converting chemical energy into mechanical force
• hydrophobic interior becomes hydrophilic, forcing burying of misfolded hydrophobic residues

Question 4

Axial domain of GroEL:

Answer 4

• forms large cavity lined with hydrophobic residues that bind unfolded proteins

Question 5

Two forms of E3:

Answer 5

• Ring E3: binds E2
• Hect E3: binds Ub via catalytic cysteine
  
  • thioester linkage

Question 6

Ubp:

Answer 6

Ub-processing proteases

• cleave isopeptide bonds between substrate and Ub
• cleave multi-Ub chains

Question 7

Intermediate domain of GroEL:

Answer 7

• forms hinge between axial and equatorial domains

Question 8

Three domains of GroEL:

Answer 8

• axial, intermediate, equatorial

Question 9

In the immunoproteasome, the 19s subunit is replaced with:

Answer 9

PA28

Question 10

CFTR^d508

Answer 10

• cystic fibrosis transmembrane receptor mutation
• mutation cause misfolding, proteolytic system captures and degrades.
  
  • however, small amount avoids degradation and become properly folded.

THIS MUTATION DECREASES OVERALL CONCENTRATION OF THIS CRITICAL TRANSPORTER.

Question 11

Equatorial domain of GroEL:

Answer 11

• contains the ATPase domain
  
  • the 7 ATPs that cause the twisting of the GroEL complex and changes the axial domain from hydrophobic to hydrophilic

Question 12

Isopeptide bond in Ub-pathway:

Answer 12

• Ub-G76 and substrate e-amino group lysine form isopeptide bond

Question 13

Peptide bond in Ub pathway:

Answer 13

• Connects Ub-fusion protein
• cleaved by Ub-carboxy-terminal-hydrolase
  
  • ATP DEPENDENT

Question 14

Thioester linkage in Ub-pathway:

Answer 14

• E1 and Ub form non-covalent linkage via Ub-adenylate
• Intramolecular rearrangement forms thioester linkage between Ub-G76 and E1-Cysteine