Molecular (Kaplan) 3

Question 1

What marks proteins for transport to the nucleus? What aa’s are prevalent in these markers?

Answer 1

Nuclear localization signals.

Lys, Pro, Arg.

Question 2

Eukaryotic EF-2 is inhibited by ADP-ribosylation by which 2 toxins?

Answer 2

Pseudomonas and Diphtheria

Question 3

What antibiotic can inhibit mitochondrial ribosomes?

Answer 3

chloramphenicol

Question 4

Puromycin is used as a selective agent in some cell culture systems. What does puromycin do?

Answer 4

Toxic to both prokaryotes and Eukaryotes, puromycin enters the A site of the ribosome, attaches to the growing peptidechain, and terminates translation.

Question 5

What does the lysosomal localization signal consist of?

Answer 5

phosphorylated mannose residues

Question 6

What directs a nascent protein to the RER?

Answer 6

hydrophobic signal sequence at the growing N-terminus

Question 7

Lysyl oxidase, which joins tropocollagen molecules into fibrils, requires what other substrate and cofactor?

Answer 7

O2 and Cu

Question 8

What is the mechanism of action of chloramphenicol?

Answer 8

Inhibits peptidyltransferase on the 50S ribosomal subunit.

Question 9

What is the mechanism of action of aminoglycosides?

Answer 9

Bind to 30S ribosomal subunit, preventing formation of the initiation complex.

Question 10

What is the mechanism of action of macrolides?

Answer 10

Bind to P-site and prevent translocation (of tRNA in ribosome).