GPI-specific phospholipase D associates with an apoA-I- and apoA-IV-containing complex.
Glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) is abundant in serum and associates with high density lipoproteins (HDL). We have characterized the distribution of GPI-PLD among lipoproteins in human plasma. Apolipoprotein (apo)-specific lipoproteins containing apoB (Lp[B]), apoA-I and A-II (Lp[A-I, A-II]), or apoA-I only (Lp[A-I]) were isolated using dextran sulfate and immunoaffinity chromatography. In six human plasma samples with HDL cholesterol ranging from 39 to 129 mg/dl, 79 +/- 14% (mean +/- SD) of the total plasma GPI-PLD activity was associated with Lp[A-I], 9 +/- 12% with Lp[A-I, A-II], and 1 +/- 1% with Lp[B]; and 11 +/- 10% was present in plasma devoid of these lipoproteins. Further characterization of the GPI-PLD-containing lipoproteins by gel-filtration chromatography and nondenaturing polyacrylamide and agarose gel electrophoresis revealed that these apoA-I-containing particles/complexes were small (8 nm) and migrated with pre-beta particles on agarose electrophoresis. Immunoprecipitation of GPI-PLD with a monoclonal antibody to GPI-PLD co-precipitated apoA-I and apoA-IV but little or no apoA-II, apoC-II, apoC-III, apoD, or apoE. In vitro, apoA-I but not apoA-IV or bovine serum albumin interacted directly with GPI-PLD, but did not stimulate GPI-PLD-mediated cleavage of a cell surface GPI-anchored protein. Thus, the majority of plasma GPI-PLD appears to be specifically associated with a small, discrete, and minor fraction of lipoproteins containing apoA-I and apoA-IV. -- Deeg, M. A., E. L. Bierman, and M. C. Cheung. GPI-specific phospholipase D associates with an apoA-I- and apoA-IV-containing complex. J. Lipid Res. 2001. 42: 442--451.
Deeg
M A
MA
Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA. mdeeg@iupui.edu
Bierman
E L
EL
Cheung
M C
MC
D000328:Adult; D000911:Antibodies, Monoclonal; D016632:Apolipoprotein A-I / Q000097:blood* / Q000494:pharmacology; D001054:Apolipoproteins A / Q000097:blood*; D008076:Cholesterol, HDL / Q000097:blood; D002850:Chromatography, Gel; D004587:Electrophoresis, Agar Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006801:Humans; D007163:Immunosorbent Techniques; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D010739:Phospholipase D / Q000097:blood*
D000911:Antibodies, Monoclonal; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D008076:Cholesterol, HDL; D017261:Glycosylphosphatidylinositols; C022205:apolipoprotein A-IV; D010739:Phospholipase D; C065017:glycoprotein phospholipase D