Phospholipids

Question 1

Phosphoglycerides

Answer 1

G3P backbone with a polar head group and two hydrophobic FA tails

Membranes

Names derived from polar head group

Root: phoshatidyl-

Question 2

Plasmalogens

Answer 2

Similar to PGs in structure

G3P backbone

C2 esterified FA

C1 FA = ether bond

Root: phosphatidal-

Expressed highly in heart and brain

Question 3

Sphingomyelin (SM)

Answer 3

Major sphingolipid found in neural membranes

Polar head group = phosphate group and choline

Question 4

Functions of phospholipids

Answer 4

1. Component of membrane
2. Emulsifier of TGs and cholesteryl esters
3. Outer coat component of plasma lipoprotein complexes
4. Pulmonary surfactant
5. Anchor proteins to the membrane
6. Enzyme activators
7. Signaling
8. Protect other membrane lipids from oxidative damage (plasmalogens - contain a vinyl either double bond)

Question 5

Which cells are NOT able to make phospholipids

Answer 5

RBCs

Question 6

Phosphogylceride synthesis

Answer 6

*begins exactly the same as TG synthesis

1. Glycerol-3P is formed from DHAP or Glycerol
   - G3P dehydrogenase or Glycerol kinase
2. 2 FAs are esterified to the C-1 and C-2 on the glycerol backbone
   - acyl transferases
3. Forms phosphatidic acid
4. Polar head is attached to the phosphate group to form a phosphogylceride (glycerophospholipid)

Question 7

Phosphoglycerides are a source for which FA…

Which is needed for eicosanoid synthesis

Answer 7

Arachidonic acid (ARA)

Question 8

Which phosphoglycerides are important sources for lung surfactant?

Answer 8

dipalmitoyl phosphatidylcholine (DPPC)

Phoshatiylglycerol (PG)

**these are the major components

The other minor ones are

PE, PI, PS

Question 9

1. Phosphatidalethanolamine
2. Phosphatidalcholine
3. Platelet-activating factor (PAF)

Answer 9

Examples of plasmalogens

1. Found in myelin sheath
2. Found in heart muscle
3. Similar to #2…but an acetyl group replaces the C2 Fatty acyl group…and the C-1 FA is saturated (usually unsaturated in plasmalogens)
   —> binds cells receptors and activates thrombotic or inflammatory events

Question 10

Degradation of phosphoglyceride (PG)

Classes of enzymes and what they cleave…

Answer 10

Phospholipase A1 and A2 = cleave the C1 and C2 FAs from the glycerol backbone

Phospholipase C (PLC) = cleaves between the glycerol backbone and the C3 phosphate group 
—> PIP2 —> DAG + IP3

***know A2 and C

Question 11

Sphingolipid synthesis overview

Answer 11

Begins with a ceramide = long chain FA attached to sphingosine through an amide bond

If phosphocholine is added to ceramide = SM

If glucose added = glucosylcerebroside

If Gal = galactosylcerbroside

Sulfatides = sulfation of the galactosylcerbroside (made in oligodendrocytes)

If >1 sugar added = a type of globoside

If sialic acid added to globoside = ganglioside