8. Fat Metabolism Flashcards
Triacylglycerols
cytoplasm of ADIPOSE cells
1 glycerol, 3 FAS
Hormonal promoters of lipolysis
Norepinephrine
Epinephrine
Glucagon
Adrenocorticotropic hormone
Fate of Glycerol
taken up by liver
Deficiency of carnitine or translocase
Muscle cramps
severe weakness
death
β-oxidation of a saturated Fatty Acid
Step wise degradation of 2C elements
Releases:
FADH2
NADH
Acetyl CoA
The Peroxisome
A secondary site for fatty acid oxidation
shortens long chain FAs
Better substrate for mitochondria uptake
Zellweger Syndrome
No functional peroxisomes
Liver, kidney and muscle abnormality
Early death
Synthesis Of Fatty Acids
Occurs In The Cytosol
Acetyl CoA + oxalacetate (4C) = citrate (6C)
citrate transported out
Formation Of Malonyl CoA
Acetyl CoA + Malonyl CoA transferred to ACP
The LDL receptor
Prevents uptake of additional cholesterol
Expression regulated by SREBP transcription factor
Loss of LDL receptor
Familial hypercholesterolemia
Blood cholesterol levels ↑
Leading to arterial narrowing
CHD
Deficiencies in LCAT and CETP
Prevents formation of cholesterol esters
free blood cholesterol accumulates in various tissues
Deficiencies in Apo E receptor
Can’t remove CM/VLDL remnants
Clinical management of Homozygous (FHC)
Liver transplant
Clinical management of Heterozygous FHC
Lower Cholesterol levels in diet
Chylomicron (CM)
fat & cholesterol from intestine
Ends up in adipose tissue to store fat
Ends up in liver for removal as a CM remnant
Very light Density Lipoprotein (VLDL)
Transports Fat from liver to Adipose tissue
Ends up back at liver as a VLDL remnant or converts to LDL
Light Density Lipoprotein (LDL)
Transports cholesterol to peripheral tissues
High Density lipoprotein (HDL)
transports chol from tissues to liver for removal
ApoB48
found on CMs
Structural function
ApoB100
On VLDLs and LDL
Targets LDLs to peripheral tissues
ApoC-II
Found on CMs & VLDLs, obtained from HDLs
Activates Lipoprotein lipase
ApoE
Found on CMs & VLDLs, obtained from HDLs
Targets CMs & VLDLs to liver for disposal
ApoA1
Found on HDLs
Activates LCAT
LDL-R
Binds Apo100 targeting LDLs to peripheral cells
Lipoprotein lipase
Found on surface of capillaries
insulin responsive activity
Hydrolyses TAG in CMs and VLDLs for transport into adipose tissue
ACAT + LCAT
Esterify cholesterol
SR-B1
Found on liver
Interacts with HDL
deposit cholesterol into hepatic cells
CETP
Pumps cholesterol from HDLs to VLDLs
ABCA1
found on surface of peripheral cells
pumps out cholesterol to HDLs
