Protein Targetting Flashcards

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1
Q

Where are proteins synthesised on free ribosome destined for

A

Cytosol, nucleus, peroxisomes and mitochondria

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2
Q

Where are protein synthesised on the RER destined for

A

Secretion, insertion into the membrane and lysosomes

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3
Q

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

A

KDEL sequence

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4
Q

Where is the KDEL sequence found on proteins

A

C terminus

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5
Q

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

A

COP1 proteins

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6
Q

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

A

N terminus

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7
Q

What type of proteins bind to proteins destined to mitochondria

A

Heat shock proteins

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8
Q

What do heat shock proteins do?

A

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

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9
Q

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

A

TOM (outer membrane) and TIM (inner membrane)

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10
Q

What happens to the protein once it enters the mitochondria

A

The protein folds and the signal sequence is cleaved

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11
Q

What is the signal sequence on proteins destined for lysosomes

A

Mannose-6-Phosphate

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12
Q

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

A

Signal patch

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13
Q

What happens to proteins once its bound to a M6P receptor

A

Transported in vesicles with a clathrate coat to lysosomes

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14
Q

What causes a dissociation between the receptor and protein

A

A pH change

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15
Q

What enzyme removes the phosphate group

A

Phophatase

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16
Q

What is I cell disease

A

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

17
Q

What is the result of I cell disease

A

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

18
Q

What is the sequence for proteins destined for the nucleus called

A

Nuclear translocation sequence

19
Q

What binds to proteins destined for the nucleus

A

Importing

20
Q

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

A

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

21
Q

What is the signal sequence for proteins targeted for peroxisomes called

A

Peroxisomes targeting sequence

22
Q

Where is the peroxisomes targeting sequence found

A

C terminus

23
Q

What recognises the peroxisomes targeting sequence

A

PEX 5 receptors

24
Q

How do proteins destined for peroxisomes enter

A

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

25
Q

What is Zellweger syndrome

A

Syndrome resulting in mutations in PEX proteins.

26
Q

What is cotranslational transport

A

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

27
Q

What 2 types of secretion are there

A

Constitutive or regulated

28
Q

Give an example of constitutive secretion

A

Collagen

29
Q

Give an example of regulated secretion

A

Insulin

30
Q

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

A

N-Terminus

31
Q

Whatcsequence is present on proteins that get inserted into the membrane

A

Stop sequence

32
Q

What shape will transmembrane domains of proteins have

A

Alpha helix