Antibiotics and Protein Regulations

Question 1

What does Streptomycin do?

Answer 1

Streptomycin inhibits initiation of prokaryotic translation by binding to the 30S subunit. This interferes with the ability of 30s to associate with the large subunit (50s)

Question 2

What does Shiga toxin do?

Answer 2

Binds to the 60S subunit in eukaryotes to disrupt elongation

Question 3

What does Clindamycin and erythromycin do?

Answer 3

Both bind to the 50s subunit to disrupt the translocation of the ribosome in prokaryotes

Question 4

What does Tetracycline do?

Answer 4

Binds to the 30s subunit of prokaryotes to disrupt elongation. Specifically it prevents entry of the aminoacyl-tRNA to the ribosome.

Question 5

What does Chloramphenicol do?

Answer 5

inhibnits peptidyl transferase activity and impairs peptide bond formation in prokaryotes.

Question 6

How does the Diptheria toxin work?

Answer 6

It inactivates the GTP bound EF-2 which will interfere with ribosomal translocation in eukaryotes

Question 7

How does cycloheximide work and what could be considered its counter part?

Answer 7

Inhibits peptidyl transferase in eukaryotes and impairs peptide bond formation. Its counterpart could be chloramphenicol

Question 8

What is the significance of puromycin?

Answer 8

causes premature chain termination in both eukaryotes and prokaryotes. It is not used clinically, but is used in labs to study translation. Specifically it enters the A site and adds to the growing chain to cause premature release of the chain.

Question 9

Describe DMD and what type of mutation causes it?

Answer 9

DMD is a defect in the dystrophin gene that causes little or non functioning dystrophin protein. Dystrophin is responsible for stabilizing the cytoskeleton and plasma membrane in muscles.

Mostly males, leads to mm wasting, wheelchair by 12 and death from respiratory failure in 20s.

Out of frame framshift deletions lead to DMD and In frame deletions lead to BMD, a less severe form with truncated forms of dystrophin.

Question 10

Describe sickle cell anemia and its mutation?

Answer 10

Is derived from a missense mutation in the Beta globin gene. The mutation changes from GAG which is Glu to GTG which is Valine. This causes a change from a negative hydrophillic amino acid to valine a hydrophobic amino acid. This causes RBC’s to sickle and therefore have poor oxygen carrying abilities and causes clogging of capillaries.

Question 11

What are the locations for the cytoplasmic pathway of protein sorting?

Answer 11

Cytosol, mt, nucleus and peroxisomes

Question 12

What are the destinations for the secretory pathway?

Answer 12

ER lysosomes plasma membrane or secretion

Question 13

You come across a protein that has a translocation signal of N terminal hydrophobic alpha helix, what is its destination?

Answer 13

Mitochondria (alpha of the cell)

Question 14

You come across a protein that has a translocation signal of KKKR, where is its destination?

Answer 14

Nucleus (dumb KKK opposite of smart nucleus)

Question 15

You come across a protein that has a translocation signal of SKL, where is it going?

Answer 15

Peroxisomes (Peroxide on SKuLl)

Question 16

You come across a protein that has a translocation signal of a N terminal apolar, where is its destination?

Answer 16

Cell membrane

Question 17

I cell disease is associated with what?

Answer 17

A defect in M6P resulting in proteins not traveling to lysosome. These end up in the blood.

Question 18

You come across a protein that has a translocation signal of Mannose 6P, where is it going?

Answer 18

Lysosome (Lick sugary(M6P) lollipop)

Question 19

You come across a protein that has a translocation signal of trp rich domains, where is it going?

Answer 19

Into a secretory vesicle to exit. (Trp makes you sleepy so you leave)

Question 20

If a protein needs to return to the ER what is its signal sequence?

Answer 20

KDEL

Question 21

You are looking at post translational modifications and you come across a lysine residue, what kind of modification would you expect to see?

Answer 21

Acetylation

Question 22

You are studying post translational modifications of proteins and you come across an O glycosylation modification. What amino acids would be associated with this?

Answer 22

Ser and Thr

Question 23

You are studying post translational modifications of proteins and you come across an N glycosylation. What amino acids would you expect to find?

Answer 23

Asn