Lipoproteins Flashcards
what disorder is caused by ApoB truncations
hypobetalipoproteinemia
what is the consequence of truncated ApoB
secreted slower and cleared faster
what are the hypobetalipoproteinemia heterozygote LDL levels
25-50% of normal
what are the consequences of hypobetalipoproteinemia
tseato-hepatitis, and homozygotes get fat soluble vit deficiency and nueromuscular degeneration
where are VLDLs with truncated ApoB cleared?
renal tubule
abetalipoproteinemia is caused by
MTP definceicy
what does MTP do?
transport TG’s and cholesterol esters onto ApoB to form VLDL
which 2 conditions are caused by excessive ApoB synthesis in the liver?
Familial combined hyperlipidemia and hyperbetalipoproteinemia
what does Hyperapobeta look like
dense ApoB-100 LDL with too much apo B
what does FCHL look like
increased number of normal VLDL
how can there be an accumulation of normal LDL in FCHL and hyperapobeta
defect in LDL clearance in addition to excess VLDL production
Is apoB production normally constant
yes
how is more lipid normally transported
bigger particles
what happens in familial hypertriglyceridemia
high liver TG synthesis, TG plasma concentration, and TG/apoB ratio
what FHT patients tend to get CVD
those with a family history of CVD
is HDL low or high in all FHT
low
what are FHT + CAD patients likely to have
insulin resistance
what things raise VLDL or TG production
dietary fat, visceral fat, high glucose, fructose, and alcohol
why are visceral adipocytes bad
they release alot of free fatty acids
what leads to visceral fat
hyperandrogenism in women, hypoandrogenism in men, and hypercortisolism
what do saturated fatty acids do
stimulate cholesterol synthesis and down regulate LDL receptors
what does LPL do
hydrolyzes CLDL and CM to free fatty acids is adipose cells, muscle cells, and macrophages
what is required for LPL
ApoCII
what inhibits LPL
ApoCIII
what does a deficiency of LPL of ApoCII do
severe hypertriglyceridemia
what does LPL biosynthesis require
small amount of insulin
what is Type I HLP
only high chylomicrons
what is Type V HLP
high VLDL and chylomicrons. clear cream and foggy plasma
what are the only things that cause Type I HLP
deficiency of LPL or ApoCII
what causes Type V HLP
VLDL over production and slight LPL abnormality
when is ApoCIII elevated
insulin resistance
does plasma TG correlate better with ApoCII or ApoCIII
ApoCIII
where is ApoE synthesized
liver. macrophages, and CNS
when is apoE secreted by macrophages
along with cholesterol
what is the main function of apoE
clearing remnants of lipoproteins
where is apoE kept
on HDL and then transferred to other particles
what protein prevents apoE from removing CMs and VLDL too soon
apoCIII
why to larger particles not bind apoE
the binding site is covered by lipid
how does apoE bind
charge interaction
what apoE phenotype is seen in familial dysbetalipoproteinemia
E2/E2
what do E2 heterozygotes get
low LDL and high TG without the disease
what do E4 people get
high LDL
