title: Apolipoprotein E activates the low-activity form of human phospholipid transfer protein.
abstract: Phospholipid transfer protein (PLTP) exists in a high-activity (HA-PLTP) and a low-activity form (LA-PLTP) in the circulation. LA-PLTP is associated with apoA-I while the HA-PLTP complex is enriched with apoE. To study the interaction of PLTP with apolipoproteins, we carried out surface plasmon resonance analyses. These demonstrated a concentration-dependent binding of recombinant human PLTP, which represents an active PLTP form, and LA-PLTP to apoE, apoA-I, and apoA-IV within a nanomolar K(D) range. To study whether LA-PLTP can be transformed into an active form, we incubated it in the presence of proteoliposomes containing apoE, apoA-I or apoA-IV. The apoE proteoliposomes induced a concentration-dependent activation of LA-PLTP. ApoA-IV proteoliposomes also activated LA-PLTP in a concentration-dependent manner, whereas apoA-I proteoliposomes had no such effect. These observations suggest that PLTP is capable of interacting with apoE, apoA-I, and apoA-IV, and that these interactions regulate PLTP-activity levels in plasma.
authors.affiliation: Department of Molecular Medicine, National Public Health Institute, Biomedicum, P.O. Box 104, FIN-00251 Helsinki, Finland.
authors.forename: Minna T
authors.initials: MT
authors.lastname: Jänis
authors.forename: Jari
authors.initials: J
authors.lastname: Metso
authors.forename: Hilkka
authors.initials: H
authors.lastname: Lankinen
authors.forename: Tomas
authors.initials: T
authors.lastname: Strandin
authors.forename: Vesa M
authors.initials: VM
authors.lastname: Olkkonen
authors.forename: Kerry-Anne
authors.initials: KA
authors.lastname: Rye
authors.forename: Matti
authors.initials: M
authors.lastname: Jauhiainen
authors.forename: Christian
authors.initials: C
authors.lastname: Ehnholm
mesh_terms: D016632:Apolipoprotein A-I / Q000378:metabolism; D001054:Apolipoproteins A / Q000378:metabolism; D001057:Apolipoproteins E / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D049294:Phospholipid Transfer Proteins / Q000378:metabolism*; D011510:Proteolipids / Q000737:chemistry; D020349:Surface Plasmon Resonance
chemical_list: D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D001057:Apolipoproteins E; D008565:Membrane Proteins; D049294:Phospholipid Transfer Proteins; D011510:Proteolipids; C020485:proteoliposomes