Binding preferences for GPIHBP1, a glycosylphosphatidylinositol-anchored protein of capillary endothelial cells.
OBJECTIVE
To define the ability of GPIHBP1 to bind other lipase family members and other apolipoproteins (apos) and lipoproteins.


RESULTS
GPIHBP1, a GPI-anchored lymphocyte antigen (Ly)6 protein of capillary endothelial cells, binds lipoprotein lipase (LPL) avidly, but its ability to bind related lipase family members has never been evaluated. As judged by cell-based and cell-free binding assays, LPL binds to GPIHBP1, but other members of the lipase family do not. We also examined the binding of apoAV-phospholipid disks to GPIHBP1. ApoAV binds avidly to GPIHBP1-transfected cells; this binding requires GPIHBP1's amino-terminal acidic domain and is independent of its cysteine-rich Ly6 domain (the latter domain is essential for LPL binding). GPIHBP1-transfected cells did not bind high-density lipoprotein. Chylomicrons bind avidly to GPIHBP1-transfected Chinese hamster ovary cells, but this binding is dependent on GPIHBP1's ability to bind LPL within the cell culture medium.


CONCLUSIONS
GPIHBP1 binds LPL but does not bind other lipase family members. GPIHBP1 binds apoAV but does not bind apoAI or high-density lipoprotein. The ability of GPIHBP1-transfected Chinese hamster ovary cells to bind chylomicrons is mediated by LPL; chylomicron binding does not occur unless GPIHBP1 first captures LPL from the cell culture medium.
Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA, USA.
Peter
P
Gin
Anne P
AP
Beigneux
Constance
C
Voss
Brandon S J
BS
Davies
Jennifer A
JA
Beckstead
Robert O
RO
Ryan
André
A
Bensadoun
Loren G
LG
Fong
Stephen G
SG
Young
D000818:Animals; D001054:Apolipoproteins A / Q000378:metabolism; D016466:CHO Cells; D002196:Capillaries / Q000166:cytology / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002914:Chylomicrons / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D008071:Lipoprotein Lipase / Q000378:metabolism; D008075:Lipoproteins, HDL / Q000378:metabolism; D009154:Mutation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D018110:Receptors, Lipoprotein; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
D001054:Apolipoproteins A; D002352:Carrier Proteins; D002914:Chylomicrons; C523701:GPIHBP1 protein, human; D008075:Lipoproteins, HDL; D018110:Receptors, Lipoprotein; D011993:Recombinant Fusion Proteins; C548261:LPL protein, human; D008071:Lipoprotein Lipase