What is the most common type of phospholipid?
glycerophospholipids
Describe a glycerophospholipid.
- glycerol backbone
- fatty acids esterified to the 1 and 2 positions (saturated 1 position, unsaturated 2 position).
- 3rd position esterified to a phosphate –> hydrophilic head group
Head Groups
Choline Ethanolamine Serine Inositol Glycerol
Phospholipid that is normally found in the cytoplasmic face of the plasma membrane; a recognition signal for clearance of RBCs or apoptosis if found in the outer leaflet
Phosphatidylserine
Phospholipid that plays an essentila role as a precursor to several biological signaling proteins (e.g. insulin signaling)
Phosphatidylinositol
Major component of lung surfactant (prevents collapse of alveoli at the end of expiration)
Phosphatidylcholine (dipalmitoyllecithin)
energy source for biosynthesis of phosphatidylcholine
CTP
Spingolipids
- based on the backbone of sphingosine (from serine and palmitate)
- all sphingolipids are derived from ceramide
- Spingosine, fatty acid, phosphate –> head group
Glycolipids
- type of sphingolipid
- sphingosine, fatty acid, carbohydrate
- always found on the outside surface of the plasma membrane
- often used by viruses or bacterial toxins to gain entry into cells
- UDP-monosaccharides are donors in the biosynthetic pathway
Sphingomyelin
- most abundant sphingolipid in humans
- highly abundant in myelin sheath surrounding nerve cells
- choline containing lipid
Nieman-Pick Disease
defects in the breakdown of sphingomyelin
Blood Group Antigens
A substance: synthesized by GalNAc transferase
B substance: synthesized by Gal transferase
-these transferases utilize UDP-monosaccharides
What inheritance pattern is seen in lysosomal storage diseases? What is the exception?
Autosomal Recessive.
Fabry’s disease is x-linked recessive.
Eicosanoid synthesis
- syntheized from polyunsaturated fatty acids containing 20 carbons, derived from linoleic and linolenic acid
- most commonly used precursor = arachidonic acid (an omega 6)
What is the most regulated step in eicosanoid synthesis?
-Phospholipase A2 (release of precursor FAs from 2-position of a membrane phospholipid)
What enzyme is used to form prostaglandins, thromboxanes and prostacyclins? (Synthesis of PGG2)
cyclooxygenase (COX1 and COX2)
- COX1 is constituitive
- COX2 is induced by cytokines
Which cyclooxygenase inhibitors are non-competitive, and which are covalent?
Aspirin = covalent
Acetaminophen and Ibuprofin = non-competitive COX inhibitors
Which enzyme is involved in the formation of Leukotrines?
Lipoxygenase
Whats is the function of Leukotrienes?
Vasoconstriction, inflammatory action. Longer half life than prostaglandins.
How does singulair work?
Singulair is a LTC4 antagonist that reduces lung inflammation and is effective in treatment of asthma.
