Evidence against phospholipid asymmetry in intracellular membranes from liver.
We have studied the distribution of phospholipids across the membrane of microsomal vesicles and Golgi-derived secretory vesicles from rat liver by the use of phospholipases. Model studies on single-bilayer phospholipid vesicles showed that phospholipase A2 (phosphatide 2-acyl-hydrolase, EC 3.1.1.4) cleaved at least 80% of the lipids on the outer surface of such vesicles without significant attack on the inner surface. In microsomal vesicles approximately 40% of the outer surface phospholipids were cleaved before the enzyme gained access to the interior of the vesicles. The same conclusion was reached for Golgi vesicles. By following the degradation of the three major phospholipids in intact microsomes and in extracted lipids we found that the same fraction of each of these phospholipids was exposed on the outer surface of the microsomal vesicles. Corresponding experiments with Golgi vesicles showed that distinctly different fractions of phosphatidylcholine and phosphatidylethanolamine were present on the surface of these vesicles. However, the difference was accounted for by enrichment of phosphatidylcholine in intravesicular particles rather than by asymmetry across the vesicle membrane. The results from specific hydrolysis of phosphatidylinositol confirmed an essentially symmetric distribution of this phospholipid across the microsomal and the Golgi vesicle membranes.
D000818:Animals; D006056:Golgi Apparatus / Q000648:ultrastructure*; D007700:Kinetics; D008099:Liver / Q000648:ultrastructure; D008297:Male; D008563:Membrane Lipids / Q000032:analysis*; D008566:Membranes / Q000648:ultrastructure*; D008862:Microsomes, Liver / Q000648:ultrastructure*; D010740:Phospholipases / Q000378:metabolism; D010743:Phospholipids / Q000032:analysis*; D051381:Rats
D008563:Membrane Lipids; D010743:Phospholipids; D010740:Phospholipases
J Biol Chem. 1964 Jul;239:2328-34
14209964
Biochem Biophys Res Commun. 1977 May 9;76(1):142-9
869943
Biochim Biophys Acta. 1976 Nov 19;450(2):154-64
10986
J Cell Biol. 1977 Mar;72(3):568-83
190241
Science. 1977 Feb 25;195(4280):743-53
402030
Biochim Biophys Acta. 1977 Jan 21;464(2):453-8
831804
J Biol Chem. 1972 Apr 25;247(8):2558-65
4336378
Biochemistry. 1973 Jun 19;12(13):2545-54
4350955
Biochemistry. 1974 Jul 2;13(14):2844-8
4407872
J Mol Biol. 1974 Aug 15;87(3):541-61
4444035
J Cell Biol. 1973 Oct;59(1):73-88
4356572
J Cell Biol. 1973 Oct;59(1):45-72
4356571
Biochim Biophys Acta. 1975 Jan 28;375(2):186-208
235977
Biochemistry. 1976 Mar 23;15(6):1277-83
1252448
Biochim Biophys Acta. 1973 Oct 11;323(2):178-93
4356540
J Clin Invest. 1976 Sep;58(3):667-80
182724
Biochemistry. 1976 Jun 1;15(11):2361-70
1276143
Biochem J. 1975 May;148(2):279-94
168886
Biochim Biophys Acta. 1975 Sep 16;406(1):83-96
169915
Biochim Biophys Acta. 1975 Dec 29;415(4):411-72
173395
J Biol Chem. 1976 Feb 25;251(4):1035-41
175064
Biochim Biophys Acta. 1973 May 24;306(2):218-26
4713151
Biochem Biophys Res Commun. 1973 Feb 20;50(4):1027-31
4690843
J Mol Biol. 1972 Nov 28;71(3):523-8
4648341
Biochim Biophys Acta. 1972 Dec 8;280(4):559-68
4648782
J Biol Chem. 1976 Aug 25;251(16):5015-26
956175
Eur J Biochem. 1976 Jan 2;61(1):53-8
1245188
Biochemistry. 1975 Nov 4;14(22):4826-30
1182120
J Cell Biol. 1975 Jul;66(1):42-59
1141379
Eur J Biochem. 1968 May;4(4):478-86
5660480