IC Compartments And Protein Sorting 2

Question 1

SAM Complex

Answer 1

• Sorting and Assemble Machinery
• Translocates beta barrel proteins on the outer membrane
• Inserts/Folds beta barrel proteins in the outer membrane

Question 2

What helps in FOLDING for the imported HSP70? How?

Answer 2

• HSP 60

- Helps by utilizing ATP

Question 3

How does bound HSP70 dissociate?

Answer 3

At the expense of ATP Hydrolysis OUTSIDE the Mitochondria

Question 4

What are the types of Mitochondrial signal sequences?

Answer 4

• N Terminal

- Internal

Question 5

Shape of SRP

Answer 5

• Rod shaped
• Large Hydrophobic pocket
  (Lined with methionines)
• Pocket can accommodate HYDROPHOBIC signal seq

Question 6

What directs proteins to the correct compartment in the Mitochondria?

Answer 6

Signal Sequences

Question 7

T/F: Proteins need to cross both Mitochondria membranes.

Answer 7

True

Question 8

Characteristics of SRP

Answer 8

• Made up of 6 diff polypeptides
• Bound to Small RNA molecule
• Cycles b/w ER membrane and cytosol
• Binds to ERSS

Question 9

What pulls the protein in the matrix?

Answer 9

Mitochondrial HSP70

Question 10

TIM22 Complex

Answer 10

• Mediates the insertion of a Specific Subclass of Proteins

eg: ATP, ADP, and Pi transporter

Question 11

What cleaves the signal sequence?

Answer 11

Signal Peptidase

Question 12

How do the precursor proteins enter the Mitochondria?

How is is maintained?

Answer 12

• Unfolded

- Maintained through interactions with CHAPERONE Proteins
Cystolic HSP70

Question 13

Characteristics of ER Signal sequences

Answer 13

• Vary in AA seq

- Has 8+ Nonpolar AA in the CENTER

Question 14

The 3 ATP dependent steps in Transport

Answer 14

1. Dissociation of the Bound HSP70
2. Protein release of HSP70
3. Folding of Protein by HSP60

Question 15

Mitochondria proteins are encoded where?

Answer 15

Nuclear DNA

Question 16

What guides ERSS to ER membrane?

Answer 16

• Signal Recognition Particle (SRP)

- SRP Receptor

Question 17

Transport of HSP70 through TIM is dependent on what?

Answer 17

Membrane Potential

Question 18

Where do the residues cluster on the helix?

Answer 18

• “+” charged residues cluster on one end

- Hydrophobic residues cluster on the other

Question 19

Signal sequences form what in the Mitochondria?

Answer 19

AMPHIPHILIC Alpha Helix

Question 20

Translocators in the Mitochondrial INNER Membrane

Answer 20

• TIM22 Complex
• TIM23 Complex
• OXA Complex

Question 21

What Complex helps to form PORIN in the Outer membrane? With the help of what?

Answer 21

• SAM Complex

- Chaperones

Question 22

OXA Complex

Answer 22

Mediates the insertion of proteins synthesized in the Mitochondria

Question 23

Parts that make up an SRP

Answer 23

• Translational pause domain
• Signal/Seq Binding pocket
• Hinge
• SRP RNA

Question 24

Translocators in the Mitochondrial OUTER Membrane

Answer 24

• TOM Complex

- SAM Complex

Question 25

TOM Complex Characteristics

Answer 25

• Translocase of OUTER membrane
• Req for IMPORT of all Nuclear encoded Proteins
• Inserts them in OUTER membrane

Question 26

TIM23 Complex

Answer 26

• Translocase of the inner membrane
• Transports SOLUBLE proteins into Matrix
• Helps insert MEMBRANE proteins in inner membrane

Question 27

Steps of Translocation across ER

Answer 27

• SRP wraps around large ribosomal subunit
• One end binds to ERSS
• One end binds to Elongation Factor binding site
• Blocks protein synthesis to let protein in the ER membrane
• SRP and Receptor released and protein is translocated across the ER membrane