W8 Eukaryotic Translation

Question 1

Eukaryotic ribosome (80S)

Answer 1

60S subunit:
-28S rRNA + 5.8S rRNA + ~50 proteins
40S subunit:
-18S rRNA + ~35 proteins

Question 2

Inhibitors of Protein Synthesis - Prokaryotes:

Answer 2

Streptomycin, neomycin, kanamycin:
- Binds to S12 protein of 30S ribosome subunit thereby inhibiting binding of tRNAfmet to the P site
-Causes misreading in a system in the act of synthesis
Chloramphenicol:
-Inhibits peptidyl transferase of 70S ribosome
Tetracylcine:
Inhibits binding of charged tRNA to 30S particle
Puromycin:
-Causes premature chain termination by acting as an analogue of charged tRNA
Fusidic acid:
-Inhibits binding of charged tRNA to A site
Kirromycin:
-Binds to EF-TU; stimulates formation of EF-TU-GTP and binding of ternary complex to ribosome
-Inhibits release of EF-TU

Question 3

Inhibitors of Protein Synthesis - Eukaryotes

Answer 3

Abrin, ricin:
-Inhibits binding of aminoacyl tRNA
Diptheria toxin:
-Enzymatic catalysis of a reaction between NAD+ and eEF2 to yield an inactive factor
-inhibits translocation
Chloramphenicol:
-Inhibits peptidyl transferase of mitochondrial ribosomes. Inactive against cytoplasmic ribosomes
Puromycin:
-Causes premature chain termination by acting as an analogue of charged tRNA
Fusidic acid:
-Inhibits translocation by altering an elongation factor
Cycloheximide:
Inhibits peptidyltransferase