%0 Journal Article %1 citeulike:637780 %A Sivaram, P. %A Choi, S. Y. %A Curtiss, L. K. %A Goldberg, I. J. %C Department of Medicine, Columbia University, New York, New York 10032. %D 1994 %J J Biol Chem %K mapping structure apob l-p-l %N 13 %P 9409--9412 %T An amino-terminal fragment of apolipoprotein B binds to lipoprotein lipase and may facilitate its binding to endothelial cells. %U http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=8144523 %V 269 %X Lipoprotein lipase (LPL), the principal enzyme which hydrolyzes triglycerides in circulating plasma lipoproteins, functions while bound to the luminal surface of endothelial cells. LPL is a heparin-binding protein and has been assumed to associate with endothelial cell heparan sulfate proteoglycans (HSPG). Recently, using ligand blotting and affinity chromatography we identified a 116-kDa heparin-releasable LPL-binding protein (hrp-116) from endothelial cells which was not a HSPG (Sivaram, P., Klein, M. G., and Goldberg, I. J. (1992) J. Biol. Chem. 267, 16517-16522). This suggested that, like a number of other heparin-binding proteins, LPL binding to cells also involves non-HSPG proteins. Using heparin-agarose affinity chromatography, a 116-kDa LPL-binding protein was purified from endothelial cell extracts. Microsequencing of peptides generated by Lys-C protease digestion revealed complete homology with four different regions in the NH2-terminal part of human apolipoprotein B (apoB). Western blots using anti-apoB monoclonal antibodies (mAb) that recognize the NH2-terminal region of apoB confirmed that a 116-kDa fragment of apoB was present on endothelial cell membranes. Further evidence that LPL associates with the NH2-terminal region of apoB was obtained by showing 1) that an NH2-terminal fragment of apoB obtained from apoB-transfected CHO cells bound LPL on ligand blots and 2) that NH2-terminal fragments of apoB generated by thrombin digestion of low density lipoprotein bind LPL. Evidence that the NH2-terminal region of apoB mediates LPL interaction with endothelial cells was obtained using monoclonal antibodies. mAb3 and mAb19, which recognize epitopes near the NH2 terminus of apoB, inhibited 125I-LPL binding to cells by 60-65%. In contrast, mAb47, which has determinants at the COOH-terminal end of apoB, inhibited LPL binding by only about 10%. The inhibitory effects of mAb3 and mAb19 were abolished following treatment of cells with heparin, which removes the 116-kDa LPL-binding protein. Furthermore, incubation of 125I-LPL in medium containing an NH2-terminal apoB fragment reduced LPL binding to cells. These data suggest that an NH2-terminal fragment of apoB that binds to endothelial surfaces facilitates LPL binding to cells.

@article{citeulike:637780, abstract = {Lipoprotein lipase (LPL), the principal enzyme which hydrolyzes triglycerides in circulating plasma lipoproteins, functions while bound to the luminal surface of endothelial cells. LPL is a heparin-binding protein and has been assumed to associate with endothelial cell heparan sulfate proteoglycans (HSPG). Recently, using ligand blotting and affinity chromatography we identified a 116-kDa heparin-releasable LPL-binding protein (hrp-116) from endothelial cells which was not a HSPG (Sivaram, P., Klein, M. G., and Goldberg, I. J. (1992) J. Biol. Chem. 267, 16517-16522). This suggested that, like a number of other heparin-binding proteins, LPL binding to cells also involves non-HSPG proteins. Using heparin-agarose affinity chromatography, a 116-kDa LPL-binding protein was purified from endothelial cell extracts. Microsequencing of peptides generated by Lys-C protease digestion revealed complete homology with four different regions in the NH2-terminal part of human apolipoprotein B (apoB). Western blots using anti-apoB monoclonal antibodies (mAb) that recognize the NH2-terminal region of apoB confirmed that a 116-kDa fragment of apoB was present on endothelial cell membranes. Further evidence that LPL associates with the NH2-terminal region of apoB was obtained by showing 1) that an NH2-terminal fragment of apoB obtained from apoB-transfected CHO cells bound LPL on ligand blots and 2) that NH2-terminal fragments of apoB generated by thrombin digestion of low density lipoprotein bind LPL. Evidence that the NH2-terminal region of apoB mediates LPL interaction with endothelial cells was obtained using monoclonal antibodies. mAb3 and mAb19, which recognize epitopes near the NH2 terminus of apoB, inhibited 125I-LPL binding to cells by 60-65%. In contrast, mAb47, which has determinants at the COOH-terminal end of apoB, inhibited LPL binding by only about 10%. The inhibitory effects of mAb3 and mAb19 were abolished following treatment of cells with heparin, which removes the 116-kDa LPL-binding protein. Furthermore, incubation of 125I-LPL in medium containing an NH2-terminal apoB fragment reduced LPL binding to cells. These data suggest that an NH2-terminal fragment of apoB that binds to endothelial surfaces facilitates LPL binding to cells.}, added-at = {2006-07-07T01:10:50.000+0200}, address = {Department of Medicine, Columbia University, New York, New York 10032.}, author = {Sivaram, P. and Choi, S. Y. and Curtiss, L. K. and Goldberg, I. J.}, biburl = {https://www.bibsonomy.org/bibtex/248a3df537415568e835d5503d2aa2937/biblio24}, citeulike-article-id = {637780}, interhash = {969077488df30f90f7eb3c45f3442f48}, intrahash = {48a3df537415568e835d5503d2aa2937}, issn = {0021-9258}, journal = {J Biol Chem}, keywords = {mapping structure apob l-p-l}, month = {April}, number = 13, pages = {9409--9412}, priority = {2}, timestamp = {2006-07-07T01:10:50.000+0200}, title = {An amino-terminal fragment of apolipoprotein B binds to lipoprotein lipase and may facilitate its binding to endothelial cells.}, url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve\&db=pubmed\&dopt=Abstract\&list_uids=8144523}, volume = 269, year = 1994 }