title: An LPL-specific monoclonal antibody, 88B8, that abolishes the binding of LPL to GPIHBP1.
abstract: LPL contains two principal domains: an amino-terminal catalytic domain (residues 1-297) and a carboxyl-terminal domain (residues 298-448) that is important for binding lipids and binding glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1 (GPIHBP1) (an endothelial cell protein that shuttles LPL to the capillary lumen). The LPL sequences required for GPIHBP1 binding have not been examined in detail, but one study suggested that sequences near LPL's carboxyl terminus (residues ∼403-438) were crucial. Here, we tested the ability of LPL-specific monoclonal antibodies (mAbs) to block the binding of LPL to GPIHBP1. One antibody, 88B8, abolished LPL binding to GPIHBP1. Consistent with those results, antibody 88B8 could not bind to GPIHBP1-bound LPL on cultured cells. Antibody 88B8 bound poorly to LPL proteins with amino acid substitutions that interfered with GPIHBP1 binding (e.g., C418Y, E421K). However, the sequences near LPL's carboxyl terminus (residues ∼403-438) were not sufficient for 88B8 binding; upstream sequences (residues 298-400) were also required. Additional studies showed that these same sequences are required for LPL binding to GPIHBP1. In conclusion, we identified an LPL mAb that binds to LPL's GPIHBP1-binding domain. The binding of both antibody 88B8 and GPIHBP1 to LPL depends on large segments of LPL's carboxyl-terminal domain.
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Christopher M
authors: CM
authors: Allan
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Mikael
authors: M
authors: Larsson
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Xuchen
authors: X
authors: Hu
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Cuiwen
authors: C
authors: He
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Rachel S
authors: RS
authors: Jung
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Alaleh
authors: A
authors: Mapar
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA.
authors: Constance
authors: C
authors: Voss
authors: Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors: Kazuya
authors: K
authors: Miyashita
authors: Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors: Tetsuo
authors: T
authors: Machida
authors: Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors: Masami
authors: M
authors: Murakami
authors: Gunma University, Graduate School of Medicine, Maebashi, Japan.
authors: Katsuyuki
authors: K
authors: Nakajima
authors: Division of Nutritional Science, Cornell University, Ithaca, NY.
authors: André
authors: A
authors: Bensadoun
authors: Finsen Laboratory, Rigshospitalet, Copenhagen N, Denmark; Biotech Research and Innovation Centre (BRIC), University of Copenhagen, Copenhagen N, Denmark.
authors: Michael
authors: M
authors: Ploug
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA. Electronic address: lfong@mednet.ucla.edu.
authors: Loren G
authors: LG
authors: Fong
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA; Human Genetics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA. Electronic address: sgyoung@mednet.ucla.edu.
authors: Stephen G
authors: SG
authors: Young
authors: Departments of Medicine University of California Los Angeles, Los Angeles, CA. Electronic address: abeigneux@mednet.ucla.edu.
authors: Anne P
authors: AP
authors: Beigneux
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000737:chemistry*; D002460:Cell Line; D004331:Drosophila melanogaster; D006801:Humans; D008071:Lipoprotein Lipase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D011485:Protein Binding; D000072417:Protein Domains; D018110:Receptors, Lipoprotein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; C523701:GPIHBP1 protein, human; D018110:Receptors, Lipoprotein; C548261:LPL protein, human; D008071:Lipoprotein Lipase
keywords: chylomicrons; endothelial cells; glycosylphosphatidylinositol-anchored high density lipoprotein binding protein 1; lipids/chemistry; lipolysis and fatty acid metabolism; lipoprotein lipase; triglycerides