You are studying cell line in which you discover that SREBP-2 is less tightly bound to the membranes of the ER. Examination of these cells shows no increase in cholesterol biosynthetic gene expression and no observable binding of SREBP-2 to the SREBPresponse element (SRE) of a known target gene. These observations can best be explained by a mutation in which of the following proteins?

Question

Quizplus · Accepted Answer

The most likely mutated protein in this case would be S2P. The reduced binding of SREBP-2 to ER membranes could most easily be explained by the normal activity of S1P. However, inability to fully release SREBP-2 would be due to ineffective S2P activity. Since S1P activity is likely normal, the mutation is not likely to be in Insig or SCAP either. The activity of SREBP-1c would have no bearing on the release of SREBP-2 from membranes.

You Are Studying Cell Line in Which You Discover That