作者: P. Sivaram , S.Y. Choi , L.K. Curtiss , I.J. Goldberg
DOI: 10.1016/S0021-9258(17)36894-1
关键词: Molecular biology 、 Epitope 、 Ligand (biochemistry) 、 Endothelial stem cell 、 Affinity chromatography 、 Biochemistry 、 Low-density lipoprotein 、 Binding protein 、 Biology 、 Apolipoprotein B 、 Lipoprotein lipase
摘要: Lipoprotein lipase (LPL), the principal enzyme which hydrolyzes triglycerides in circulating plasma lipoproteins, functions while bound to luminal surface of endothelial cells. LPL is a heparin-binding protein and has been assumed associate with cell heparan sulfate proteoglycans (HSPG). Recently, using ligand blotting affinity chromatography we identified 116-kDa heparin-releasable LPL-binding (hrp-116) from cells was not HSPG (Sivaram, P., Klein, M. G., Goldberg, I. J. (1992) Biol. Chem. 267, 16517-16522). This suggested that, like number other proteins, binding also involves non-HSPG proteins. Using heparin-agarose chromatography, purified extracts. Microsequencing peptides generated by Lys-C protease digestion revealed complete homology four different regions NH2-terminal part human apolipoprotein B (apoB). Western blots anti-apoB monoclonal antibodies (mAb) that recognize region apoB confirmed fragment present on membranes. Further evidence associates obtained showing 1) an apoB-transfected CHO 2) fragments thrombin low density lipoprotein bind LPL. Evidence mediates interaction antibodies. mAb3 mAb19, epitopes near NH2 terminus apoB, inhibited 125I-LPL 60-65%. In contrast, mAb47, determinants at COOH-terminal end only about 10%. The inhibitory effects mAb19 were abolished following treatment heparin, removes protein. Furthermore, incubation medium containing reduced These data suggest binds surfaces facilitates