The Acidic Domain of GPIHBP1 Is Important for the Binding of Lipoprotein Lipase and Chylomicrons Export

@article{citeulike:3426258, abstract = {GPIHBP1, a glycosylphosphatidylinositol-anchored endothelial cell protein of the lymphocyte antigen 6 (Ly6) family, plays a key role in the lipolysis of triglyceride-rich lipoproteins (e.g. chylomicrons). GPIHBP1 is expressed along the luminal surface of endothelial cells of heart, skeletal muscle, and adipose tissue, and GPIHBP1-expressing cells bind lipoprotein lipase (LPL) and chylomicrons avidly. GPIHBP1 contains an amino-terminal acidic domain (amino acids 24-48) that is enriched in aspartate and glutamate residues, and we previously speculated that this domain might be important in binding ligands. To explore the functional importance of the acidic domain, we tested the ability of polyaspartate or polyglutamate peptides to block the binding of ligands to pgsA-745 Chinese hamster ovary cells that overexpress GPIHBP1. Both polyaspartate and polyglutamate blocked LPL and chylomicron binding to GPIHBP1. Also, a rabbit antiserum against the acidic domain of GPIHBP1 blocked LPL and chylomicron binding to GPIHBP1-expressing cells. Replacing the acidic amino acids within GPIHBP1 residues 38-48 with alanine eliminated the ability of GPIHBP1 to bind LPL and chylomicrons. Finally, mutation of the positively charged heparin-binding domains within LPL and apolipoprotein AV abolished the ability of these proteins to bind to GPIHBP1. These studies indicate that the acidic domain of GPIHBP1 is important and that electrostatic interactions play a key role in ligand binding. 10.1074/jbc.M802579200}, author = {Gin, Peter and Yin, Liya and Davies, Brandon S. and Weinstein, Michael M. and Ryan, Robert O. and Bensadoun, Andre and Fong, Loren G. and Young, Stephen G. and Beigneux, Anne P.}, citeulike-article-id = {3426258}, citeulike-linkout-0 = {http://dx.doi.org/10.1074/jbc.M802579200}, citeulike-linkout-1 = {http://www.jbc.org/cgi/content/abstract/283/43/29554}, citeulike-linkout-2 = {http://view.ncbi.nlm.nih.gov/pubmed/18713736}, citeulike-linkout-3 = {http://www.hubmed.org/display.cgi?uids=18713736}, doi = {10.1074/jbc.M802579200}, journal = {J. Biol. Chem.}, keywords = {acidic, binding, chylomicrons, gin08pdf, lipase, lipoprotein, region}, month = {October}, number = {43}, pages = {29554--29562}, posted-at = {2008-10-18 00:28:05}, priority = {2}, title = {The Acidic Domain of GPIHBP1 Is Important for the Binding of Lipoprotein Lipase and Chylomicrons}, url = {http://dx.doi.org/10.1074/jbc.M802579200}, volume = {283}, year = {2008} }

TY - JOUR ID - citeulike:3426258 L3 - citeulike-article-id:3426258 N2 - GPIHBP1, a glycosylphosphatidylinositol-anchored endothelial cell protein of the lymphocyte antigen 6 (Ly6) family, plays a key role in the lipolysis of triglyceride-rich lipoproteins (e.g. chylomicrons). GPIHBP1 is expressed along the luminal surface of endothelial cells of heart, skeletal muscle, and adipose tissue, and GPIHBP1-expressing cells bind lipoprotein lipase (LPL) and chylomicrons avidly. GPIHBP1 contains an amino-terminal acidic domain (amino acids 24-48) that is enriched in aspartate and glutamate residues, and we previously speculated that this domain might be important in binding ligands. To explore the functional importance of the acidic domain, we tested the ability of polyaspartate or polyglutamate peptides to block the binding of ligands to pgsA-745 Chinese hamster ovary cells that overexpress GPIHBP1. Both polyaspartate and polyglutamate blocked LPL and chylomicron binding to GPIHBP1. Also, a rabbit antiserum against the acidic domain of GPIHBP1 blocked LPL and chylomicron binding to GPIHBP1-expressing cells. Replacing the acidic amino acids within GPIHBP1 residues 38-48 with alanine eliminated the ability of GPIHBP1 to bind LPL and chylomicrons. Finally, mutation of the positively charged heparin-binding domains within LPL and apolipoprotein AV abolished the ability of these proteins to bind to GPIHBP1. These studies indicate that the acidic domain of GPIHBP1 is important and that electrostatic interactions play a key role in ligand binding. 10.1074/jbc.M802579200 IS - 43 JF - J. Biol. Chem. EP - 29562 TI - The Acidic Domain of GPIHBP1 Is Important for the Binding of Lipoprotein Lipase and Chylomicrons VL - 283 SP - 29554 KW - acidic KW - binding KW - chylomicrons KW - gin08pdf KW - lipase KW - lipoprotein KW - region AU - Gin, Peter AU - Yin, Liya AU - Davies, Brandon AU - Weinstein, Michael AU - Ryan, Robert AU - Bensadoun, Andre AU - Fong, Loren AU - Young, Stephen AU - Beigneux, Anne PY - 2008/10/24/ UR - http://dx.doi.org/10.1074/jbc.M802579200 ER -