Question

Which of these is not a response to ER stress?

a. Expansion of the ER

b. Upregulation of the gene encoding the translocon

c. Inhibition of protein translation

d. Increased expression of genes encoding molecular chaperones

e. Apoptosis

I think A and E are true, but I'm not sure about B-D

Answer 1

ER stress occurs when the capacity of the ER to fold proteins becomes abnormal and is saturated. ER stress may be caused by factors the impairment in the glycosylation or disulfide bond formation in the protein, or by overexpression of mutated proteins or mutation of the protein involved in signal transduction.

a. Expansion of the ER: ER stress induces ER expansion via the formation of membrane sheets. Exposure of cells DTT ca cause ER stress.

b. Upregulation of the gene encoding the translocon: The translocon proteins that are helping to transports the nascent polypeptides with signal sequence into the interior (cisternal or lumenal) space of the endoplasmic reticulum (ER) from the cytosol the transport proteins are downregulated because the ER is already under stress and cannot afford to have a large number of transported protein inside it.

c. Inhibition of protein translation: ER stress involved recovery from inhibition of stress-induced protein synthesis.

d. Increased expression of genes encoding molecular chaperones: Transcriptional induction of genes encoding ER chaperones that assist the conformational folding or unfolding and the assembly or disassembly of the protein structures.

e. Apoptosis: ER stress-induced cell death. Under ER stress, the enzyme cascade induce to follow the programmed cell death.

Thus, the answer is b. Upregulation of the gene encoding the translocon

Thank you!