W3-4 Cholesterol Metabolism Flashcards
Ultimate precursor of all cholesterol synthesized de novo
Acetyl-CoA
How many carbons is cholesterol? Made from how many acetyl-CoAs?
27 C
from 15 acetyl-CoAs
Rate determining/drug targeting step
HMG-CoA reductase
blocked by statins
How is cholesterol synthesis regulated on transcription level?
What promotes the degradation of HMG-CoA reductase?
High sterol levels
How is HMG-CoA reductase regulated on a whole-body metabolism level?
2 ways liver ships cholesterol
VLDLs
bile acids
Chylomicrons in intestinal epithelium cells
nascent chylomicrons
(nascent means ‘new’)
This Apo protein is always present on chylomicrons
ApoB-48
HDLs add this apoprotein to chylomicrons to activate them
ApoC II
Chylomicrons are mostly what?
TAGs
Cholesterol is often bound to what molecule for transport from the liver?
FA
This apo protein is always bound to VLDLs
ApoB-100
HDLs add which apoprotein to VLDLs to activate them?
ApoC II
Draw out VLDL and chylomicron activation and metabilism in blood
Familial hypercholesterolemia pathology
LDL receptor miscoding, does not allow LDLs to be endocytosed
Xanthoma
subcutaneous fat deposits
Describe how atherosclerotic plaques are formed
- Excess LDLs captured under intima of blood vessels
- Macrophages consume this fat and become foam cells
- Foam cells die and leave plaque
Three metabolic uses of cholesterol
Membranes
Steroid hormones
Bile acids
Congenital adrenal hyperplasia
Disease in women that causes increased androgen synthesis and decreased cortisol and androgen synthesis
Steroid hormones act through what type of regulation?
transcriptional
