Sunday, March 31, 2013

Lipoproteins and apoproteins

Hey guys!
We have always had difficulty remembering lipoproteins and apoproteins and stuff.. And what makes it simpler? Mnemonics!

After you eat, dietary trigylcerides is transported via chylomicrons from the intestine to the adipose tissue.
VLDL carries endogenous triglycerides from the liver to the peripheral tissues.

Both triglyceride transporters contain apoB

Chylomicrons have micro
Micro means small
So they have a small number, that is, apoB 48

VLDL have the larger number, apoB 100

apoC II is a Cofactor for lipoprotein lipase
Which hydrolyzes the triglycerides into fatty acids and glycerol
LIpoprotein LIpase is activated by InsuLIn

apoE helps in rEmnant uptake by lEvEr (Liver =P )

Chylomicron (B48, C-II, E) > Chylomicron remnant (B48, E)
 

VLDL (B100, C-II, E) > IDL (B100, E) > LDL (B100)
VLDL loses apoC-II to become IDL
IDL loses apoE to become LDL
LDL will transport cholesterol to peripheral tissues

apoA-I Activates lcAt (LCAT)
Also, I looks like l
It's on HDL
Converts cholesterol to cholesterol esters
(LCAT transfers a polyunsaturated fatty acid from 2nd carbon of glycerol to cholesterol forming lysolecithin and cholesterol ester)

*phew* That was work!
Let's have a look at the deficiencies now =)

So what happens if you have apoB deficiency?
No triglycerides is incorporated into VLDL and chylomicrons
Serum triglycerides, cholesterol and phospholipids are low
Beta lipoprotein (LDL) is absent
Lipids and lipid-soluble vitamins (especially A and E) are poorly absorbed (steatorrhea)
Hemolytic anemia—lipid imbalance causes RBC membranes to pucker (acanthosis)

What happens in lipoprotein lipase deficiency?
Increased triglycerides in chylomicrons and VLDL!
(You can't breakdown triglycerides to fatty acid and glycerol for uptake)

What happens if you have a LDL receptor deficiency?
There will be and increased levels of LDL and cholesterol
(Because peripheral tissues can't take them without the LDL receptor)

What happens if you have LCAT deficiency?
You have increased unesterified cholesterol
(You can esterify the cholesterol you have)
You also have increased phoshatidyl choline which is a component of lecithin

That's all!
 Have an awesome week <3

-IkaN

Post is continued here

16 comments:

  1. This is awesome!

    ReplyDelete
  2. Replies
    1. Thanks. Have a brilliant day! :D

      Delete
  3. It's truly amazing!!

    ReplyDelete
  4. So what happens if you have apoB deficiency?
    No triglycerides is incorporated into VLDL and chylomicrons
    Serum triglycerides, cholesterol and phospholipids are low.

    But defective apoB 100 causes familial hypercholesterolemia.

    ReplyDelete
    Replies
    1. I'm not sure. Need to brush up my biochemistry. I will get back to you later. Lemme know if you find the answer.

      Delete
    2. "Defective apoB 100 causes familial hypercholesterolemia"

      → That's because the defect lies in the binding ability of apoB-100 to LDL receptor.
      Since the liver cannot uptake LDL efficiently, there will be high LDL, resulting in hypercholesterolemia.

      Check it out here:
      http://www.jlr.org/content/31/8/1337.full.pdf
      (There is a chapter "CONSEQUENCES OF THE MUTATION IN APOLIPOPROTEIN B-100 ON BINDING To THE LOW DENSITY LIPOPROTEIN RECEPTOR")

      Delete

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