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Cell > 02.16- Protein Processing > Flashcards

02.16- Protein Processing Flashcards

1
Q

What are the three basic post-translation processes?

A

Cleaving
Altering
Degrading

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2
Q

Which of the following is incorrect?

a. Trypsinogen is a zymogen of trypsin.
b. The inactive form of chymotrypsin is chymotrypsinogen.
c. Proinsulin is activated by altering.
d. Caspases are activated by cleavage of procaspases

A

c. Proinsulin is activated by altering. (The formation of insulin from proinsulin is due to cleavage.)

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3
Q

What type of post-translational modification is characterised by covalent attachment of chemical groups to proteins?

A

Altering

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4
Q

An example of protein altering that is characterised by the addition of carbohydrates is called?

A

Glycosylation

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5
Q

What sugar is attached to proteins targeted by lysosomal digestion?

A

Mannose-6-phosphate

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6
Q

What Vitamin C-dependent protein altering mechanism is important in modifying proline and lysine residues in collagen?

A

Hydroxylation

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7
Q

The formation of gamma-carboxyglutamate from glumatate residues is due to what type of covalent modification?

A

Carboxylation

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8
Q

Attachment of lipids for anchoring proteins to membranes is called:

A

Farnesylation

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9
Q

What regulatory protein tags aberrant proteins for proteasomal digestion?

A

Ubiquitin

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10
Q

What structure destroys ubiquitin-tagged proteins?

A

Proteasome

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11
Q

True or False: Procollagen may undergo multiple modifications before becoming collagen.

A

True (hydroxylation, oxidation, cleavage, etc.)

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12
Q

True or False: There is no structural difference between ribosomes found in the cytosol and ribosomes found in the RER.

A

True

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13
Q

What are the two protein sorting pathways in the cell?

A

Cytosolic pathway

Rough ER pathway

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14
Q

Enumerate the cellular components that acquire proteins via the cytosolic pathway.

A

Nucleus
Peroxisome
Mitochondria
Cytosol

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15
Q

Enumerate the cellular components that acquire proteins via the RER pathway.

A

Membranes
Lysosomic enzymes
Secretory protein

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16
Q

True or False: It is hypothesised that all protein synthesis begins in free ribosomes, unless that ribosome is directed to the rough ER.

A

True

17
Q

Arrange the steps of the signal hypothesis in order (no choices):

I - Release of SRP
II - Attachment of SRP to the signal sequence
III - Translocation of polypeptide chain into the ER lumen
IV - Synthesis of the signal sequence
V - Binding of SRP-bound signal sequence to SRP receptor
VI - Cleavage of signal sequence by signal peptidases

A

IV-II-V-I-III-VI

18
Q

What amino acid sequence directs the protein to further translation in the nucleus?

A

Nuclear Localization Proteins

19
Q

What amino acid sequence directs the protein to further translation in the peroxisome?

A

Peroxisomal-matrix targeting sequences

20
Q

The targeting proteins to the matrix signals the protein to undergo further translation in which organelle?

A

Mitochondria

21
Q

After cleavage of the signal sequence by signal peptidases in the ER lumen, the polypeptide then proceeds to which organelle?

A

Golgi apparatus (for further modification and export)

22
Q

Which of the following does not use receptor-mediated endocytosis?

a. LDL uptake
b. Waste disposal of haemoglobin complexes
c. Digestion of defective mitochondria
d. Mucosal transfer/transcytosis of IgA

A

c. Digestion of defective mitochondria (This is macroautophagy.)

23
Q

What proteins are responsible for receptor-mediated endocytosis?

A

Clathrin and adaptin

24
Q

What protein is responsible for phagoycytosis?

A

Actin

25
Q

Which of the following is not a lipid-storage disease?

a. Neimann-Pick
b. Tay-Sachs
c. Hurler
d. Farber

A

c. Hurler

26
Q

Pompe is what type of lysosomal storage disease?

A

Glycogen-storage disease

27
Q

Which of the following is not true about chaperones?

a. They are located only in the ribosomes and RER.
b. They are responsible for binding to hydrophobic areas.
c. They have ATPase activity.
d. They do not promote protein folding but only prevents improper folding.

A

a. They are located only in the ribosomes and RER.

Chaperones are located almost everywhere just like ubiquitin.

28
Q

What is the affected protein in cystic fibrosis? Familial hypercholesterolemia?

A

CFTR, LDL receptor

29
Q

What substance inhibits eEF-2?

A

Diphtheria toxin

30
Q

What substance inactivates 28S rRNA?

A

Ricin

31
Q

This substance is an aminonucleoside analogue that binds to the A-site of the ribosome.

A

Puromycin

32
Q

This family of substances inhibits the 30S subunit by preventing initiation.

A

Aminoglycosides

33
Q

This substance inhibits the 30S subunit by preventing binding of aminoacyl tRNAs to the A-site.

A

Tetracycline

34
Q

What is responsible for inhibiting peptidyltransferase in the 50S subunit?

A

Chloramphenicol

35
Q

What drugs acts on the 50S subunit and inhibits translocation?

A

Clindamycin/erythromycin

36
Q

What substance inhibits the 23S subunit?

A

Macrolides

37
Q

What substance binds to the eukaryotic 60S subunit?

A

Cycloheximide

Cell (18 decks)

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