lipoproteins Flashcards

Question

what are y-migrating lipoproteins

Answer 1

apoE-only HDL

Answer 2

LpX and Lp(a)

Answer 3

lipoprotein (a) Lp(a)

Answer 4

LpB lipoproteins separated by protein content affinity chromatography for apolipoproteins

Answer 5

* Density is directly proportional with percent protein content and percent phospholipid content * Density is inversely proportional with triglyceride content

Answer 6

* Density is directly proportional with percent protein content * Density is inversely proportional with size, PL content, CE content, TG content, and FC content

Answer 7

apo): a protein that is void of lipid that can associate with lipoproteins

Answer 8

* There are close to 200 known proteins that can associate with lipoproteins: – some have functions associated with lipoprotein metabolism – some just hitch a ride to be delivered to tissues

Answer 9

* ApoB48 & apoB100 NEVER fall off a lipoprotein; they are non-exchangeable * All other apo’s can fall off a lipoprotein; they are exchangeable

Answer 10

two step model * The synthesis of VLDL occurs in the liver: – Requires apoB100, lipids (TG, PL, FC, CE), & microsomal triglyceride transfer protein (MTP) – Occurs co-translationally/co-translocationally – Slow process: 20 minutes for one VLDL

Answer 11

* ApoB-48 = 48% of the apoB-100 protein (...apoB-100 = 100%) * ApoB-48 is generated in the intestine through the enzymatic removal of an amine group (‘deamination’) from a specific cytidine on the mRNA sequence for apoB-100 to generate uracil – this introduces a stop codon ~48% into the apoB-100 mRNA sequence

Answer 12

ApoB’s act as integral proteins that maintain the structure of chylomicrons, VLDL, IDL, and LDL – Both apoB’s are huge proteins – Both apoB’s wrap around its lipoprotein

Answer 13

Only one apoB-48 is present on a chylomicron, and only one apoB-100 is present on VLDL, IDL, or LD

Answer 14

* The apoB mRNA is translated in the cytosol into protein * During apoB protein synthesis, the growing peptide is translocated from the cytosol into the endoplasmic reticulum – aka start of the cell secretory pathway * The packaging of lipids with apoB occurs simultaneously as the protein is being translated and translocated

Answer 15

Microsomal triglyceride transfer protein (MTP)

Answer 16

* MTP plays a critical role in the first step of VLDL synthesis * MTP transfers stored triglycerides, as well as some phospholipids and cholesteryl esters, to apoB: – This occurs during apoB translocation and also during apoB100 transport through the endoplasmic reticulum

Answer 17

The absence of MTP prevents VLDL synthesis and leads to apoB degradation

Answer 18

triacylglycerol hydrolase

Answer 19

* TGH hydrolyses triglycerides stored in large cytosolic lipid droplets into glycerol and three fatty acids

Answer 20

* The hydrolysis products are liberated from the lipid droplets into the cytosol, where they are used toward re-synthesizing triglycerides

Answer 21

* The newly synthesized triglycerides are thought to form their own small sized lipid droplet * This small lipid droplet is incorporated as a whole with VLDL 2 to yield a larger sized VLDL 1

Answer 22

* ApoB100 synthesis * Microsomal triglyceride transfer protein (MTP) * Phosphatidic acid phosphatase (PAP), also known as lipin-1