Complex Lipids 1 Flashcards
What are the components of Gylcerophospholipids?
Glycerol backbone + 2 FA (joined by ester bonds) + “polar head group”
Head Groups include: choline, ethanolamine, serine, inositol, glycerol
TAG has a glycerol backbone and 3 FA joined by ester bonds
both are types of “glycerolipids”
How is glycerol-3-p in the fed state (for complex fatty molecule synthesis) synthesized:
a) in the liver?
b) in adipose tissue?
a) conversion from glycerol by ATP hydrolysis and glycerol kinase (only occurs in the liver!) or by conversion from DHAP (from glycolysis)
b) by conversion from DHAP (from glycolysis)
What is the role of glyceroneogenesis in adipose tissue?
Under fasting conditions, glycerolneogenesis (made from lactate, AAs, and pyruvate) in the adipose cell can regulate FA release after glucagon by re-esterifying f.a. to Glycerol-3-P made from Glyceraldehyde3P. E.g. Pyr to OAA to PEP to 2PG to 3PG TO 1,3BPG to G3P. As much as 30-40% of fa released by hormone sensitive lipase are re-esterified. (Hormone would be glucagon, or epinephrine.)
Mice engineered without this pathway for glycerolneogenesis in fat cells release abnormally high FA in the blood in fasting and have low fat stores. Mice with overactive PEPCK the controlling enzyme for glycerolneogenesis have lower FA release and are obese.
What happens to the gylcerol-3-p in triglyceride synthesis?
addition of two fatty acyl CoA’s (activated by ATP) makes phosphatidic acid
What happens to phosphatidic acid?
it is de-phosphorylated to become diacylglycerol
What happens to diacylglycerol?
addition of another fatty acyl CoA makes TAG
What happens to the TAG in a) liver b) adipose
a) packaged in VLDL (TAG with Apo100)
B) stored
What complex lipids are commonly found on the inner side of the plasma membrane?
glcyerophospholipids (sphingolipids common on the outside of the plasma membrane for cell-cell recognition)
What are the different types of phospholipases and what do they do?
these cleaves glycerophospholipids
A1- cleaves the 1 FA
A2- cleaves the 2 FA
C- cleaves the head of of the lipid with phosphate attached to the head
D- cleaves the head of the lipid without the phosphate attached to the head
How are phosphatidylserine, phosphatidylethanolamine, and phosphatidylcholine synthesized from phosphatidic acid?
an activated CDP-head group is added to a diacylglycerol to form a glycerophospolipid
in reality, only phosphatidylethanolamine and phosphatidylcholine are made this way. phosphatidylserine is made by exchange of ethanol amine by serine from phosphatidylethanolamine
How are phosphatidylinositol, cardiolipin, and How are phosphatidylglycerol made from phosphatidic acid?
diacyglycerol is activated by CTP (forms CDP-diacylglycerol) and then a head group is added to form a glycerophospholipid
Where is phosphatidylcholine commonly found?
a subtype of phosphatidylcholine (dipalmitoylphosphatidylcholine)- aka lecithin- forms a majority of the composition of surfactant
Neonatal respiratory distress syndrome
deficiency of surfactant due to lack of lecithin
What does “stimulus” binding of hormone do to a) phosphatidylcholine
b) phosphatidylcholine bisphosphate
a) stimulates phospholipase A2 to cleave the 2 FA from phosphtdylcholine to form arachidonic acid (a precursor for eicosanoid synthesis- involved in signal transduction)
b) stimulates phospholipase C to cleave 1,2 diacylglycerol head group, which can form arachidonic acidd (a precursor for eicosanoid synthesis- involved in signal transduction)
