Question

Cholesterol sensing by SREBP-2 in the ER membrane signals for increased transcription of:

A) LDL receptors
B) HMG-CoA reductase
C) HDL cholesterol
D) Cholesterol esters

Answer 1

Cholesterol sensing by SREBP-2 increases the transcription of LDL receptors to facilitate cholesterol uptake, and HMG-CoA reductase to enhance cholesterol synthesis when intracellular cholesterol levels are low. Therefore, the correct option is A, B.

Step-by-step explanation:

Cholesterol sensing by SREBP-2 in the ER membrane signals for increased transcription of both LDL receptors and HMG-CoA reductase. The SREBP-2 (Sterol Regulatory Element Binding Protein-2) pathway is crucial in cholesterol homeostasis; when cellular cholesterol levels are low, SREBP-2 is activated and enters the nucleus to promote transcription of genes involved in cholesterol uptake and synthesis. This includes upregulation of LDL receptors to increase uptake of cholesterol through LDL particles from the bloodstream and enhancing the production of HMG-CoA reductase, a key enzyme in the cholesterol biosynthesis pathway.