lipoproteins Flashcards
lipoproteins consist of
-neutra lipid core-tag and cholestryl esters
- shell of amphipathic apoliporptoetine, phospho, nonesterfifie(free)cholestol
size and density
chylomicrons: lowest density, contain most lipid /TAG, least protein
vldl and ldl: denser and higher protein than lipid
hdl: smalles and densest
apolipoprotins function
activator or coexnyme for enzymes in metbaolsim
essential compinent of particles
provide recognition sites for cells urfave receptors
chylomicron assembled in, funciton
in intestinal mucosa
- carry diestary/Exogenous TAG, choelstrol, fat soluble vitamins and choelstryl esters to peripheral tissues
apo b-48 is unique where and where is it assembled
chylomicrons
begins on RER), move thorugh RER and GA
Assevmbluu of apo b-48 and lipid into chylo reuires whta
microsomal triglyceride transfer protein (MTP)–>load apo med lipid
- before er to GA
what is LPL and what does it do
enxyme tht degrades the TAG contained in chylomicrons–>FAs and glycerol
- ancchored to capillary walls, expecially adipose tissue and cardiac and skeletal
- ## act by apo c-2
how is LPL regulated
nutritianal and hormonal level
fed state: increased synthesis in adipose, decreased in muscle
fasting: opposute
in chylomoicron remnant formation, what happens to apoliproteins
- apo c is returned to HDL
- apo b and e stays
- remainng particle is removed for circulation by liver. the liver have lipoprotein receptors that recognize apo E. take –>heppatocytes by endocytosis. –>lysosome and hydrolysis happens–>AAs, free cholestrol and FA
where are vldl produced and what do they consist of(function)
liver
endogenous TAG, carry this lipid form the liver–>peripheral tissues
which apolipoprotein do vldl contain
vldl secreted dirctly into blood by liver as anscent aprticles with apo b-100.
Get apo e and c2 form HDL
how do vldl becomes denser
degraded by TAG and appo e and c2 is returned.
-apob-100 retains
- some tag –>hdl. hdl give cholestryl esters . need choelstryl ester transfer protein
whta do ldl have high concentration of and what is their function
choelstrol and cholestryl esters
provide cholestrol to the peripheral tossues or return it to the liver
how do ldl do their task
bind to plasma membrane lld recprot that recognize apo b-100 (not apo b-48)
how does chylomicron remnant, idl and ldl derived cholestrol affect cellular choelstrol content
-high cholestrol inhibit hmg reducate=>de novo cholestorl synthesis decrease
- choelstrol not required: acat esterifies it . transfer FA from a afatyy acyl coa to cholestrol , producing a cholestryl ester that can be stored in cells
ldl uptake by macrophage sacvenger receptors
scavenger receptor class a bind to ligands and mediate endocytosis
SR is not downgraded by intracellular cholestrol
cholesteryl esters accumulate in macrophages and cause their transformation into foam cells–>participate in formation of atherosclerotic plaque
where are hdl formed an dfunction
in blood by addition of apo A-1(liver and intestine)
serve as resercoir of apo C-2 (transferred to vldl and chylo, act of LPL)
what do nascent hdls contain+function
apo a, c and e
take up choelstrol form nonheptic (peripheral ) tissues and return it to liver as cholestryl esterss
how is choelstrol esterified in hdl
by plasma enzyme lecithin:cholestrolacyltransferase (LCAT) activated by APO A-1.
- Transfer FA from c2 of PC to choelstrol
what is effluc of choelstrol form peripheral cells mediated by
transport ptorin ABCA1
what is choelstryl ester uptake by liver mediated by
cell surfcae receptor scavenger receptor class B type 1
what is homolog to plasminogen
apo (A), the precursor of blood protease whose target is fibrin. fibrin is main component of blood clots
where are steroid hormones synthesized and secretion
adrenal cortex
aldosterone
- poduced in outer layer of adrenal cortex
- induced by decrease in plasma Na+/potassium K+ and by hormone angiotensin II
