Sphingomyelinase activity associated with human plasma low density lipoprotein - Possible functional implications

被引:52
作者
Holopainen, JM [1 ]
Medina, OP [1 ]
Metso, AJ [1 ]
Kinnunen, PKJ [1 ]
机构
[1] Univ Helsinki, Dept Med Chem, Inst Biomed, Helsinki Biophys & Biomembrane Grp, FIN-00014 Helsinki, Finland
关键词
D O I
10.1074/jbc.275.22.16484
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Isolated human plasma low density lipoprotein (LDL) was observed to possess sphingomyelinase activity. Accordingly, the formation of ceramide was catalyzed by LDL at 37 degrees C using tertiary Liposomes composed of sphingomyelin (mole fraction (x) = 0.2), 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (x = 0.7), 1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol (x = 0.1), and either the fluorescent sphingomyelin analog Bodipy-sphingomyelin or [C-14]sphingomyelin as substrates. However, this activity was not present in either very low density lipoprotein or the high density lipoprotein subfractions HDL2 and HDL3. Oxidation of LDL abrogated its sphingomyelinase activity. Aggregation of the liposomes upon incubation with LDL was evident from the light scattering measurements. Microinjection of LDL to the surface of giant liposomes composed of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), N-palmitoyl-D-sphingomyelin (C16:0-sphingomyelin), and Bodipy-sphingomyelin as a fluorescent tracer (0.75:-0.20:0.05, respectively) revealed the induction of vectorial budding of vesicles, resembling endocytosis.
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页码:16484 / 16489
页数:6
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