Answer to Question #283808 in Cell Biology for fati

Question

Answer all of the following questions concerning protein synthesis by the endoplasmic reticulum: (Total of 7 Marks) a. Name the structure that binds to the SRP at the honest of secretory protein synthesis. (1 Mark) b What happens to protein synthesis when the above binding (a) is established on the nascent polypeptide chain? (1 Mark) c What facilitates the association of the ribosome with the translocon of the ER membrane? (2 Mark) d. Which molecule recognizes and binds to unfolded or misfolded proteins and help them attain their native structure. (1 Mark) e. Which molecule is responsible for degrading misfolded proteins? (1 Mark) t. Where are misfolded secretory proteins eventually destroyed? (1 Mark)

Answer 1

a. Ribosome-nascent chain complex (RNC)

b. SRP binds the ribosome as well as the signal sequence, inhibiting further translation and targeting the entire complex.

c. Membrane-bound ribosomes, attached to the cytosolic side of the ER membrane, are engaged in the synthesis of proteins that are being concurrently translocated into the ER. ... When a ribosome happens to be making a protein with an ER signal sequence, the signal directs the ribosome to the ER membrane.

d. Molecular chaperones

e. ubiquitin

f. The endoplasmic reticulum