11.21 D Flashcards
Which lipoprotein doesn’t express B48 or B100?
HDL
Which lipoprotein expresses B48 in place of B100?
chylomicrons
What is the function of apoB-100?
it is the ligand for LDL receptor
What is the function of apoB-48?
it is structural
What is the function of apoC-II?
it is an activator of lipoprotein lipase
What is the function of apoE?
it is a ligand for the LDL receptor
Which apoproteins are ligands for the LDL receptor?
apoE and apoB-100
apoE is included in what lipoproteins?
chylomicrons and HDL which don’t express apoB-100
What is the function of apoA-1?
an activator of lecithin:cholesterol acyltransferase (LCAT)
What is the function of lecithin: cholesterol acyltransferase (LCAT)?
esterify cholesterol for transport
What is the function of lipoprotein lipase?
hydrolyzes triglycerides into fatty acids for uptake into tissue
Where is LPL expressed?
in blood vessels
What is the function of hepatic triglyceride lipase (HTGL)?
to hydrolyze triglycerides that are arriving at the liver
What is the function of cholesteryl ester transfer protein (CETP)?
to transfer cholesterol esters form one lipoprotein to another
What is the function of the ABC proteins involved in lipid transport?
they are resposible for the efflux of cholesterol from tissue into HDL
What is the function of SR-A?
it is found on macrophages for foam cell formation
What is the function of SR-B?
found on hepatocytes for HDL uptake
What is acid lipase?
a lipase found in lysosomes that functions at low pH to hydrolyze cholesterol
What is the function of LDL-receptor related protein?
uptake of cholesterol-loaded chylomicron remnants and HDL as well as the delivery of cholesterol to the liver for excretion
Dietary triglycerides get packaged into what lipoproteins?
chylomicrons
What is the basic role of chylomicrons?
to take dietary triglycerides to the tissues where LPL removes them, leaving a chylomicron remnant which then takes cholesterol to the liver
What carries fatty acids from tissue to the liver?
albumin
What carries triglycerides from the liver to peripheral tissues?
VLDL
In what two ways is cholesterol excreted from the body?
directly or as bile salts produced in the liver
Cholesterol leaves the liver packaged in what sort of lipoprotein?
a VLDL
What happens to VLDL remnants?
- uptake by hepatic LDL receptors
- hydrolysis by HTGL to form LDL
To go from a nascent HDL to a mature HDL, what enzyme is required?
LCAT
What are the two possible fates of HDL?
- transfer of cholesteryl esters to VLDL by CETP
- direct liver uptake of cholesteryl esters by SR-B1 receptor
The ABC transporters are important for what liver function?
bile acid production for biliary lipid secretion
What is the function of ABCG5/G8?
transport of cholesterol into canaliculi in liver
What is the function of ABCB11?
transport of bile acids into canaliculi in liver
What is the function of ABCB4?
transport of phospholipids into canaliculi in liver
What is the function of ABCA1?
export of cholesterol and phospholipids to lipid-poor apolipoprotein A1
What is the function of ABCG1?
promote efflux of cellular cholesterol to HDL particles
ABCA1 and ABCG1 are critical to what lipid metabolic process?
reverse cholesterol transport via HDL
Reverse cholesterol transport is mediated by what lipoprotein?
HDL
What genetic defects would lead to high LDL cholesterol?
apoB, apoE, or LDL receptor defects
What genetic defects would lead to low HDL cholesterol levels?
apoA-1 or ABCA1
What genetic defects would cause VLDL or chylomicron triglyceride levels to be high?
defects in apoC-II (activator of LPL), LPL, or LCAT (esterifies cholesterol for packing into HDL)
What genetic defect would lead to high levels of chylomicron remnants and intermediate density lipoproteins?
apoE which is a hepatic LDL receptor for VLDL remnants and IDLs
What happens to plasma LDL that is not taken up by hepatic LDL receptors?
it migrates into vascular intima to be taken up by scavenger receptors
HDL is important and beneficial because it performs what function?
draws free cholesterol from cholesterol-rich cells
HDL is synthesized where?
in the liver and intestine
HDL decreases the among of cholesterol available for tissue deposition by doing what?
removing it from macrophages and promoting its return to the liver
When testing for lipoprotein disorders, you should measure ____ when?
serum lipids after a 10 hour fast
Primary hypertriglyceridemia is characterized by what?
high triglycerides
What is the most common form of primary hypertriglyceridemia?
familial hypertriglyceridemia of unknown genetic cause
What are two rare primary hypertriglyceridemias?
- familial lipoprotein lipase deficiency
- apoC-II deficiency
Familial hypercholesterolemia is due to what genetic defect?
the LDL receptor
When do cholesterol levels get elevated in someone with familial hypercholesterolemia?
at birth
When do triglyceride levels get elevated in someone with familial hypertriglyceridemia?
upon weight gain, aging, onset of diabetes, etc.
What are cutaneous xantomas?
cholesterol deposits seen in those with homozygous familial hypercholesterolemia
What is dysbetalipoproteinemia due to?
a defect in apoE causing a rise in chylomicrons and IDL-like particles
Tangier disease is due to what deficiency?
ABCA1, which is responsible for HDL formation
