Protein Transport

Question 1

Core of 6-12 hydrophobic AA proceeded by one or more basic AA

Answer 1

ER

Question 2

3-5 non consecutive Arg or Lys . . often contains ser or Thr, amphipathic helix

Answer 2

Mitochondria

Question 3

Ser–Lys–Leu (SKL)

Answer 3

Peroxisomes

Question 4

5 basic AA

Answer 4

Nucleus

Question 5

Nuclear pores . . .

Answer 5

Occludes proteins > 60 kd. Hydrophobic (phenylalanine and glycine core). Requires a truck to dump stuff in.

Question 6

Alpha importin

Answer 6

Recognizes the NLS and binds the NLS.

Question 7

Beta Importin

Answer 7

Mediates docking with the outer surface of the nuclear pore in an energy independent fashion.

** Allows the complex to shoot through the nuclear pore (phenylalanine and glycine complex).

Question 8

Carries the Ran GDP in

Answer 8

NTF2

Question 9

Ran GTP does what?

Answer 9

Knocks the cargo off once in the nucleus.

Question 10

After Ran GTP knocks off the cargo , , , what happens ?

Answer 10

Ran GTP binds to alpha importin and the importin/RanGTP complex can leave the nucleus.

Question 11

RanBP what’s it do

Answer 11

Takes RanGTP off of importin complex once it is back in the cytoplasm.

Question 12

After RanBP takes off the RanGTP from the importin complex in the cytoplasm, what happens to RanBP?

Answer 12

RanBP now possesses what it took off from the importin complex (RanGTP). And now. . Ran GAP turns the RanGTP in the cytoplasm to RanGDP so now the GDP can go out into the nucleus for the cycle to repeat.

Question 13

Ran GEF

Answer 13

Turns RanGDP to RanGTP in the nucleus so that RanGTP can unload more cargo.

Question 14

Ligand induced NLS activation

Answer 14

Binding of ligand causes NLS to move to outside.

Question 15

NLS is only imported when it is

Answer 15

Dephosphorylated

Question 16

At the start of the cell cycle when the lamins become phosphorylated, the 1.?

When de-phos, . . . 2.?

Answer 16

1. Break up

2. Reassemble (GTP dependent)

Question 17

Mitochondrial transport is

Answer 17

POST-translational
** ANd requires energy !!

** And nuclear proteins have to be imported into mitochondria.

Question 18

100% required for mitochondrial protein transport

Answer 18

1. Electrochemical gradient
2. Aliphatic positively charged helix
3. Chaperones (Hsp-70s)

Question 19

Outer and inner chaperones

Answer 19

Outer -unfolds proteins

Inner -ratchets the proteins in.

Question 20

Can the signal sequence be removed in the mitochondria?

Answer 20

Yes

Question 21

Big thing about peroxisomes

Answer 21

Plasmolegens

Question 22

Main peroxisomal targeting sequence is at which term ?

Answer 22

C term . . . SKL

Question 23

Transporter to peroxisomes

Answer 23

PEKS 5

Question 24

Substitution of what amino acid leads to what disease regarding peroxisomes . . .

Answer 24

Alanine glyoxylate aminotransferase.

Leads to hyperoxaluria.

Results in renal failure.

Question 25

Does peroxisomal transport require ATP or membrane potential?

Answer 25

ATP,but no membrane potential.

Question 26

What carries the cargo into the peroxisomes and what does the carrier do?

Answer 26

Forms the gate itself.

Question 27

Channel into peroxisomes is recycled how

Answer 27

ATP hydrolysis after it becomes ubiquitinated.

Question 28

Zellwegar syndrome

Answer 28

Defect in getting many protein to peroxisomes.

AR

Caused by absence of Pex5p receptor.

Enzymes such as catalase will be found in the cytoplasm rather than in peroxisomes.

Question 29

Familial hyper cholesterol is caused by

Answer 29

Mutation in LDL receptor

Autosomal Dominant

Question 30

Statins are inhibitors of

Answer 30

3-hydroxy-3-methyl-glytaryl-coenzyme A reductase

Question 31

Common ligand that binds to LDL receptor

Answer 31

B-100