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A pressure‐dependent model for the regulation of lipoprotein lipase by apolipoprotein C‐II
Author(s) -
Meyers Nathan,
Larsson Mikael,
Olivecrona Gunilla,
Small Donald
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.886.8
Subject(s) - lipoprotein lipase , chemistry , desorption , phospholipid , lipoprotein , apolipoprotein b , adsorption , surface pressure , biochemistry , biophysics , chromatography , enzyme , cholesterol , organic chemistry , biology , physics , membrane , mechanics
Apolipoprotein C‐II (apoC‐II) is the co‐factor for lipoprotein lipase (LPL) at the surface of triacylglycerol‐rich lipoproteins. LPL hydrolyzes triacylglycerol, which increases local surface pressure as amphipathic products accumulate at the lipoprotein surface. To understand how apoC‐II adapts to these pressure changes, we characterized the behavior of apoC‐II at lipid/water interfaces. ApoC‐II adsorption to a triacylglycerol/water interface resulted in large increases in surface pressure. ApoC‐II was exchangeable at this interface and desorbed on interfacial compressions. These compressions increase pressure and mimic the actions of LPL. Analysis of gradual compressions showed that apoC‐II undergoes a two‐step desorption. This indicates that lipid‐bound apoC‐II exhibits multiple conformations. We characterized apoC‐II at phospholipid/triacylglycerol/water interfaces, which more closely mimic lipoprotein surfaces. ApoC‐II molecules completely desorbed on interfacial compressions at retention pressures higher than those of the other apoCs. It is therefore unlikely that apoC‐I and apoC‐III inhibit LPL via displacement of apoC‐II from lipoproteins. On rapid compressions and re‐expansions, re‐adsorption of apoC‐II increased pressure by lower amounts than initial adsorption. This indicates that apoC‐II removes phospholipid from the interface on desorption. These results suggest that apoC‐II regulates the activity of LPL in a pressure‐dependent manner. ApoC‐II binds lipoproteins and is the co‐factor for LPL as pressure increases. Above its retention pressure, apoC‐II desorbs and removes phospholipid, which allows LPL to remain bound.