RAT #16 - CoTranslational Translocation

Question 1

Which of following is NOT of Signal Recognition Particle?

a. temporarily arrests translation
b. binds to an SRP receptor at the translocon
c. it has signal peptidase activity
d. binds to the signal sequence of secreted proteins

Answer 1

c. it has signal peptidase activity

Question 2

{True / False}

All proteins, including cytoplasmic proteins such as ribosomal proteins, contain an ERSS.

Answer 2

FALSE

Question 3

When compared to free polyribosomes in the cytosol, rough ER-bound ribosomes have:

a. exactly the same small and large subunits
b. the same large subunits but different small subunits
c. the same small subunits but different large subunits
d. different large and small subunits

Answer 3

a. exactly the same small and large subunits

Question 4

{True / False}

Proteins of the secretory pathway are transferred into the endoplasmic reticulum at the same time as they are being synthesized by ER Ribosomes.

Answer 4

TRUE

Question 5

What is the name of the sequence in a protein that determines that it (the protein) is to be transferred to the endoplasmic reticulum?

a. ER Translocation Sequence
b. ER Signal Sequence
c. ER Import Sequence
d. ER Localization Signal
e. Enhancer Sequence

Answer 5

b. ER Signal Sequence

Question 6

Which of the following proteins would possess an ER signal sequence?

a. TFIID general transcription factor
b. lysosomal enzyme
c. DNA Polymerase
d. H1 histone protein

Answer 6

b. lysosomal enzyme

Question 7

Which of the following is NOT a component of the ER Translocon?

a. SEC 61 (pore complex)
b. ribosome receptor
c. mRNA receptor
d. SRP receptor

Answer 7

c. mRNA receptor

Question 8

Which of the following proteins is NOT synthesized by Cytoplasmic Ribosomes?

a. ER chaperone protein
b. Telomerase
c. Topoisomerase
d. RNA Polymerase

Answer 8

a. ER chaperone protein

Question 9

As the amino terminus of a protein emerges from the ribosome, an ERSS is recognized and bound by a?

a. ER Ribosome
b. Signal Peptidase
c. tRNA
d. ER Translocon
e. Signal Recognition Particle

Answer 9

e. Signal Recognition Particle

Question 10

Where in a protein is the signal sequence located for targeting proteins to the ER?

a. 3’ UTR
b. amino terminus
c. carboxy terminus
d. 5’ UTR

Answer 10

b. amino terminus