Protein Targetting

Question 1

Where are proteins synthesised on free ribosome destined for

Answer 1

Cytosol, nucleus, peroxisomes and mitochondria

Question 2

Where are protein synthesised on the RER destined for

Answer 2

Secretion, insertion into the membrane and lysosomes

Question 3

What sequence do proteins destined to remain in the Er contain?

Answer 3

KDEL sequence

Question 4

Where is the KDEL sequence found on proteins

Answer 4

C terminus

Question 5

What proteins transport proteins with the KDEL sequence back to the ER

Answer 5

COP1 proteins

Question 6

Where is the signal sequence for proteins destined to go to mitochondria found?

Answer 6

N terminus

Question 7

What type of proteins bind to proteins destined to mitochondria

Answer 7

Heat shock proteins

Question 8

What do heat shock proteins do?

Answer 8

Allow proteins to cross the mitochondrial membrane and pull the protein through the translocation machinery

Question 9

What are the 2 translocation machine dies found the in the mitochondrial membranes

Answer 9

TOM (outer membrane) and TIM (inner membrane)

Question 10

What happens to the protein once it enters the mitochondria

Answer 10

The protein folds and the signal sequence is cleaved

Question 11

What is the signal sequence on proteins destined for lysosomes

Answer 11

Mannose-6-Phosphate

Question 12

What do proteins destined for mitochondria contain to be recognised by enzymes that their mannose region needs phosphorylating

Answer 12

Signal patch

Question 13

What happens to proteins once its bound to a M6P receptor

Answer 13

Transported in vesicles with a clathrate coat to lysosomes

Question 14

What causes a dissociation between the receptor and protein

Answer 14

A pH change

Question 15

What enzyme removes the phosphate group

Answer 15

Phophatase

Question 16

What is I cell disease

Answer 16

Deficiency in the Kinase enzyme which phosphorylates the mannose group for proteins destined for lysosomes

Question 17

What is the result of I cell disease

Answer 17

Bloated lysosomes as they don’t have enzymes to break down their contents

Question 18

What is the sequence for proteins destined for the nucleus called

Answer 18

Nuclear translocation sequence

Question 19

What binds to proteins destined for the nucleus

Answer 19

Importing

Question 20

What is the role of Ran GTP in protein targeting for the nucleus

Answer 20

Binds to importin causing a conformational change which displaces the cargo protein

Question 21

What is the signal sequence for proteins targeted for peroxisomes called

Answer 21

Peroxisomes targeting sequence

Question 22

Where is the peroxisomes targeting sequence found

Answer 22

C terminus

Question 23

What recognises the peroxisomes targeting sequence

Answer 23

PEX 5 receptors

Question 24

How do proteins destined for peroxisomes enter

Answer 24

PEX proteins make up a complex in th emebrsne and form a pore

Question 25

What is Zellweger syndrome

Answer 25

Syndrome resulting in mutations in PEX proteins.

Question 26

What is cotranslational transport

Answer 26

When proteins move from ribosomes to the Golgi then out of the cell

Question 27

What 2 types of secretion are there

Answer 27

Constitutive or regulated

Question 28

Give an example of constitutive secretion

Answer 28

Collagen

Question 29

Give an example of regulated secretion

Answer 29

Insulin

Question 30

Where is the signal sequence found for proteins destined to be secreted

Answer 30

N-Terminus

Question 31

Whatcsequence is present on proteins that get inserted into the membrane

Answer 31

Stop sequence

Question 32

What shape will transmembrane domains of proteins have

Answer 32

Alpha helix