Acyl chain unsaturation in PEs modulates phase separation from lipid raft molecules.
By one hypothesis, phospholipids containing unsaturated fatty acids may be involved in phase separation from the lipid raft molecules sphingomyelin (SM) and cholesterol (CHOL). We tested the effect of increasing the number of double bonds in the acyl chains of phosphatidylethanolamines (PEs) on phase separation from SM/CHOL. The detergent extraction method was employed on various homoacid and heteroacid PEs in mixed vesicles composed of PE/SM/CHOL (1:1:1mol). The disaturated homoacid 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (16:0-16:0PE) showed the least solubility upon detergent extraction whereas maximal solubility was observed for the polyunsaturated homoacid 1,2-didocosahexaenoyl-sn-glycero-3-phosphoethanolamine (22:6-22:6PE). Increasing the number of double bonds in the sn-2 position of heteroacid saturated-unsaturated PEs resulted in an increase in detergent solubility, which correlated with a general decrease in the gel-to-liquid crystalline phase transition temperature of the PEs. Our findings demonstrate that increasing unsaturation in PEs results in increased phase separation from SM/CHOL membranes, which may have implications for cellular signaling.
Raza Shaikh
Saame
S
Department of Biology, Indiana University Purdue University Indianapolis, 723 W Michigan Street, Indianapolis, IN 46202-5132, USA.
Dumaual
Alfred C
AC
LoCassio
Daniel
D
Siddiqui
Rafat A
RA
Stillwell
William
W
D002152:Calorimetry, Differential Scanning; D002784:Cholesterol / Q000737:chemistry; D003902:Detergents / Q000494:pharmacology; D005227:Fatty Acids / Q000737:chemistry; D008055:Lipids; D021962:Membrane Microdomains / Q000737:chemistry*; D010714:Phosphatidylethanolamines / Q000737:chemistry; D013109:Sphingomyelins / Q000737:chemistry; D013696:Temperature
D003902:Detergents; D005227:Fatty Acids; D008055:Lipids; D010714:Phosphatidylethanolamines; D013109:Sphingomyelins; D002784:Cholesterol