Abstract
Plasma phospholipid transfer protein (PLTP) plays an important role in the maintenance of plasma high-density lipoprotein (HDL) content and remodeling of HDL in the circulation. In the present study we have used different fractionation methods to investigate the distribution of PLTP in human plasma. A novel enzyme-linked immunosorbent assay developed during the study allowed for simultaneous assessment of both PLTP mass and activity in the fractions obtained. Size-exclusion chromatography and plasma fractionation by nondenaturing polyacrylamide gel electrophoresis (PAGE) yielded similar results demonstrating that PLTP associates in native plasma with two distinct particle populations, while ultracentrifugation with high salt leads to detachment of PLTP from lipoprotein particles and loss of a majority of its phospholipid transfer activity. Interestingly, analysis of the size-exclusion chromatography fractions demonstrated that PLTP exists in the circulation as an active population that elutes in the position of HDL corresponding to an average molecular mass of 160 ± 40 kDa and an inactive form with an average mass of 520 ± 120 kDa. The inactive fraction containing approximately 70% of the total PLTP protein eluted between HDL and low density lipoprotein (LDL). Thus, the two PLTP pools are associated with different types of lipoprotein particles, suggesting that the PLTP activity in circulation is modulated by the plasma lipoprotein profile and lipid composition.—Oka, T., T. Kujiraoka, M. Ito, T. Egashira, S. Takahashi, M. N. Nanjee, N. E. Miller, J. Metso, V. M. Olkkonen, C. Ehnholm, M. Jauhiainen, and H. Hattori. Distribution of phospholipid transfer protein in human plasma: presence of two forms of phospholipid transfer protein, one catalytically active and the other inactive. J. Lipid Res. 2000. 41: 1651–1657.
Highlights
Plasma phospholipid transfer protein (PLTP) plays an important role in the maintenance of plasma highdensity lipoprotein (HDL) content and remodeling of HDL in the circulation
SDS-polyacrylamide gel electrophoresis (PAGE) and immunoblot analysis revealed that these antibodies recognized a single 80-kDa band in human plasma that corresponds to the mobility of purified human plasma PLTP (Fig. 1)
The distribution of phospholipid transfer protein (PLTP) in human plasma was analyzed by three methods, ultracentrifugation, nondenaturing polyacrylamide gradient gel electrophoresis (ND-PAGE), and size-exclusion chromatography
Summary
Plasma phospholipid transfer protein (PLTP) plays an important role in the maintenance of plasma highdensity lipoprotein (HDL) content and remodeling of HDL in the circulation. Proteins associated with some of the HDL subpopulations are Abbreviations: apo, apolipoprotein; CETP, cholesteryl ester transfer protein; CHD, coronary heart disease; CHO, Chinese hamster ovary; ELISA, enzyme-linked immunosorbent assay; HDL, high density lipoprotein; HRP, horseradish peroxidase; kDa, kilodalton; LDL, low density lipoprotein; LPDP, lipoprotein-deficient plasma; MAb, monoclonal antibody; ND-PAGE, nondenaturing polyacrylamide gradient gel electrophoresis; OPD, o-phenylenediamine; PBS, phosphate-buffered saline; PC, phosphatidylcholine; PL, phospholipid; PLTP, phospholipid transfer protein; PVDF, polyvinylidene difluoride; rhPLTP, recombinant human PLTP; SDS-PAGE, sodium dodecyl sulfate-polyacrylamide gel electrophoresis; TBS, Tris-buffered saline; VLDL, very low density lipoprotein. After hydrolysis of triglyceride-rich lipoproteins, surface remnant lipids are transferred to HDL and constitute precursors of HDL This transfer is promoted by PLTP [13]. The remodeling of HDL by PLTP is influenced by the protein composition of the particle [18] and is enhanced significantly by the presence of triglyceride in the HDL particles [19]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
