Deck 8: Protein Targeting

Question 1

The most promising gene therapy strategy for I-cell disease is to:

A)Introduce an intact copy of the a-L-iduronidase gene.
B)Replace a normal copy of the iduronate sulfatase gene with one containing a nuclear localization signal.
C)Replace the N-acetyl-galactosamine transferase gene with one containing a lysosomal localization signal.
D)Replace a faulty copy of the mannose-6-phosphate transferase gene with a functional copy.
E)Replace all lysosomal enzyme genes.

Answer 1

Replace a faulty copy of the mannose-6-phosphate transferase gene with a functional copy.

Question 2

In glycoproteins, the terminal position in the oligosaccharide is most commonly occupied by:

A)N-acetylglucosamine.
B)Glucose.
C)Mannose.
D)Iduronic acid.
E)N-acetylneuraminic acid.

Answer 2

N-acetylneuraminic acid.

Question 3

Misfolded proteins accumulate in some age-related degenerative diseases.Normally, however, misfolded proteins are escorted to the proteosome for destruction.This process begins with the covalent attachment of the protein:

A)Ubiquitin.
B)Adaptin.
C)Clathrin.
D)Tubulin.
E)Dolichol.

Answer 3

Ubiquitin.

Question 4

The first step in the post-translational processing of secreted proteins in eukaryotes is:

A)Proteolytic removal of the first two or three amino acid residues from the amino terminus by the signal recognition particle.
B)Attachment of a mannose-rich oligopeptide to asparagine side chains.
C)Attachment of mannose-6-phosphate to the protein.
D)Proteolytic cleavage by signal peptidase.
E)Formation of disulfide bonds.