Lehninger PPT Ch10
Lehninger PPT Ch10
Lehninger PPT Ch10
Lipids
Lipids: Structurally Diverse Class
The molecular structures of two types of membrane lipid classes are similar.
Phosphatidylcholine (a glycerophospholipid) and sphingomyelin (a sphingolipid)
have similar dimensions and physical properties, but presumably play different
roles in membranes.
Ether Lipids: Plasmalogen
• Vinyl ether analog of
phosphatidylethanolamine
• Common in vertebrate heart
tissue
• Also found in some protozoa
and anaerobic bacteria
• Function is not well
understood Ether lipids. Plasmalogens have an ether-linked
– Resistant to cleavage by alkenyl chain where most glycerophospholipids have
common lipases but an esterlinked fatty acid. . Platelet-activating factor
has a long ether-linked alkyl chain at C-1 of glycerol,
cleaved by few specific
but C-2 is ester-linked to acetic acid, which makes the
lipases
compound much more water-soluble than most
– Increase membrane glycerophospholipids and plasmalogens. The head-
rigidity? group alcohol is ethanolamine in plasmalogens and
– Sources of signaling choline in platelet-activating factor.
lipids?
– May be antioxidants?
Ether Lipids: Platelets-Activating Factor
• Aliphatic ether analog of phosphatidylcholine
• Acetic acid has esterified position C2
• First signaling lipid to be identified
• Stimulates aggregation of blood platelets
• Plays role in mediation of inflammation
Ether lipids Platelet-activating factor has a long ether-linked alkyl chain at C-1 of glycerol, but
C-2 is ester-linked to acetic acid, which makes the compound much more water-soluble than most
glycerophospholipids and plasmalogens. The head-group alcohol is ethanolamine in
plasmalogens and choline in platelet-activating factor.
Sphingolipids
The molecular structures of two types of membrane lipid classes are similar.
Phosphatidylcholine (a glycerophospholipid) and sphingomyelin (a sphingolipid)
have similar dimensions and physical properties, but presumably play different
roles in membranes.
Sphingomyelin is structurally similar
to phosphatidylcholine
Gal
Defects in the turnover of membrane
lipids lead to a number of diseases